Encryption in Access Control

Encryption in Access Control

In the process of sending information from sender to receiver, an unauthorized user may work in an active way (update it) or passive way (read or delay in sending). There must be some techniques which assures receiver that whatever information received from authorized user as well as must be same as sent from sender side, in addition to this receiver never make Denial of service. Nowadays sharing of information or resources is a very common thing from single user to the network to the cloud. When information is moving from one node to another node, security is a big challenge. When information is stored on the user’s computer, it is under control but when it is in movement user lose control over it. In the world of security, to convert information from one form to another form, Encryption is used, so that only authorized party will able to read. Encryption is a technique for any security-conscious organization.

Access control is one of the techniques for security for providing integrity and confidentiality. Its main task is to regulate the sharing of resources or information. Access control denotes whether a particular user has rights to perform particular operation on particular data. Access control policies define the users’ permission in order to provide security. These policies are defined according to an access control model. It prevents unauthorised sharing of resources or information. It also secures data against internal attacks and disclosure, leakage of information to cyberterrorist.

As an RFID access card gets close to its reader, it begins to wirelessly transmit its binary code. If using 125KHz proximity, then the wireless protocol is typically Wiegand, an older technology that can no longer provide the security needed today. In a worst case scenario, hackers could simply lift that fixed Wiegand clear text, retransmit it to the card reader and, from there, physically enter the facility and thereby the network, allowing these characters free rein to target the IT system. Data encryption is part of good practice and is, indeed, an opportunity for the security industry.

Mostly Access control is user identification to do a specific job, provide authentication, then provide that person the right to access data This is just like granting an individual permission to log in to network using name and password, allowing then to use resources after confirming whether they have permit to do particular job. So, how to provide permission to a particular user to perform their task? Here access control is used.

There are three major elements to access control system encryption:

Authentication: Determining whether someone is, in fact, who they say they are. Credentials are compared to those on file in a database. If the credentials match, the process is completed and the user is granted access. Privileges and preferences granted for the authorized account depend on the user’s permissions, which are either stored locally or on the authentication server.    The settings are defined by an administrator. For example, multifactor authentication, using a card plus keypad, has become commonplace for system logins and transactions within higher security environments.

Integrity: This ensures that digital information is uncorrupted and can only be accessed or modified by those authorized to do so. To maintain integrity, data must not be changed in transit; therefore, steps must be taken to ensure that data cannot be altered by an unauthorized person or program. Should data become corrupted, backups or redundancies must be available to restore the affected data to its correct state.  Measures must also be taken to control the physical environment of networked terminals and servers because data consistency, accuracy and trustworthiness can also be threatened by environmental hazards such as heat, dust or electrical problems. Transmission media (such as cables and connectors) should also be protected to ensure that they cannot be tapped; and hardware and storage media must be protected from power surges, electrostatic discharges and magnetism.

Non-repudiation: This declares that a user cannot deny the authenticity of their signature on a document or the sending of a message that they originated. A digital signature – a mathematical technique used to validate the authenticity and integrity of a message, software or digital document – is used not only to ensure that a message or document has been electronically signed by the person, but also to ensure that a person cannot later deny that they furnished it, since a digital signature can only be created by one person.

Here is Encryption Algorithms

1. AES

The Advanced Encryption Standard (AES) is the algorithm trusted as the standard by the U.S. Government and numerous organizations.

Although it is extremely efficient in 128-bit form, AES also uses keys of 192 and 256 bits for heavy duty encryption purposes.

AES is largely considered impervious to all attacks, with the exception of brute force, which attempts to decipher messages using all possible combinations in the 128, 192, or 256-bit cipher. Still, security experts believe that AES will eventually be hailed the de facto standard for encrypting data in the private sector. AES-128, AES-192 and AES-256 module is FIPS 140-2 certified. “FIPS mode” doesn't make Windows more secure. It just blocks access to newer cryptography schemes that haven't been FIPS-validated.

2. Twofish

Computer security expert Bruce Schneier is the mastermind behind Blowfish and its successor TrueCrypt. Keys used in this algorithm may be up to 256 bits in length and as a symmetric technique, only one key is needed.

Twofish is regarded as one of the fastest of its kind, and ideal for use in both hardware and software environments. Like Blowfish, Twofish is freely available to anyone who wants to use it. As a result, you’ll find it bundled in encryption programs such as PhotoEncrypt, GPG, and the popular open source software TrueCrypt.

3. Triple DES

Triple DES was designed to replace the original Data Encryption Standard (DES) algorithm, which hackers eventually learned to defeat with relative ease. At one time, Triple DES was the recommended standard and the most widely used symmetric algorithm in the industry.

Triple DES uses three individual keys with 56 bits each. The total key length adds up to 168 bits, but experts would argue that 112-bits in key strength is more like it.

Despite slowly being phased out, Triple DES still manages to make a dependable hardware encryption solution for financial services and other industries.

Here is How Encryption Works

Encryption consists of both an algorithm and a key. Once a number is encrypted, the system needs to have a key to decrypt the resultant cyphertext into its original form. There are two varieties of algorithms— private (symmetric) and public (asymmetric).

Private key encryption uses the same key for both encryption and decryption. Be aware—if the key is lost or intercepted, messages may be compromised. Public key infrastructure (PKI) uses two different but mathematically linked keys. One key is private and the other is public.

With PKI, either key can be used for encryption or decryption. When one key is used to encrypt, the other is used to decrypt. The public portion of the key is easily obtained for all users. However, only the receiving party has access to the decryption key allowing messages to be read. Systems may use private encryption to encrypt data transmissions but use public encryption to encrypt and exchange the secret key.

Using one or both these algorithms, access credential communications may be encrypted. Many modern cards support cryptography. Look for terms such as 3DES, AES (which the government uses to protect classified information), TEA and RSA.

Adding Encryption to an Access Control System

Integrators should consider 13.56 MHz smart cards to increase security over 125 KHz proximity cards. One of the first terms you will discover in learning about smart cards is “Mifare,” a technology from NXP Semiconductors.

The newest of the Mifare standards, DESFire EV1, includes a cryptographic module on the card itself to add an additional layer of encryption to the card/reader transaction. This is amongst the highest standard of card security currently available. DESFire EV1 protection is therefore ideal for sales to customers wanting to use secure multi-application smart cards in access management, public transportation schemes or closed-loop e-payment applications.

Valid ID is a relatively new anti-tamper feature available with contactless smartcard readers, cards and tags. Embedded, it adds yet an additional layer of authentication assurance to traditional Mifare smartcards. Valid ID enables a smartcard reader help verify that the sensitive access control data programmed to a card or tag is indeed genuine and not counterfeit.

Encrypted Cards and Readers Inhibit Hackers

Whether you need to guard against state sponsored terrorists or the neighborhood teen from hacking the electronic access control systems that you implement, security today starts with encryption. But, that’s just a beginning. To take steps that will further hinder hackers, ask for your manufacturer’s Cybersecurity Vulnerability Checklist.

While many believe that opening their network to cloud services might welcome greater risks, these studies and common mishaps suggest otherwise. Lack of employee education or defined cyber security policies, gaps in physical security and insufficient system maintenance contribute to the greatest number of threats.

How Connected Applications are Shaping Up to Be More Secure

Cloud is not all or nothing. Cloud services can be added to complement an on-premises system and its infrastructure. This can include using cloud applications to store long-term evidence, instead of on local servers or on external storage devices which can end up in the wrong hands. Cloud services can also play a critical role in disaster recovery.

In case servers are damaged by a fire or natural disaster, a full system back-up can be restored using cloud services so operations can continue without delay. Organizations can connect on-premises systems to cloud services to strengthen security and minimize internal and external threats. Here is how.

Automating Updates to Avoid Known Vulnerabilities

Many vulnerabilities that hackers prey on are quickly identified and fixed by vendors in software version updates. Even when an IT team sets scheduled updates in a closed environment, it might not happen fast enough to prevent a breach. The perk of deploying cloud services is that system updates are facilitated by the vendor. As soon as the latest versions and fixes are available, the client will have access to them. This helps to ensure that their systems are always protected against known vulnerabilities.

Considering Security in the Selection of Your Cloud Service Provider

All cloud solutions are not created equally. To identity the most secure cloud services, it’s important for organizations to take a closer look at the vendor’s security policies and built-in security mechanisms. This should include encrypted communications, data protection capabilities, and strong user authentication and password protection.

These mechanisms help protect organizations against hackers and other internet- based attacks. From an internal standpoint, they also ensure only those with defined privileges will be able to access or use resources, data and applications.

Organizations should also look at the back-end cloud platform on which the services are built. Tier-one cloud providers such as Microsoft have a global incident response team that works around the clock to mitigate attacks. The company also builds security into its cloud platform from the ground up, embedding mandatory security requirements into every phase of the development process. Top cloud providers also go out of their way to comply with international and industry-specific compliance standards, and participate in rigorous third-party audits which test and verify security controls.

NFC to Be More Secure

Nowadays a set of short range wireless technologies is use for public transport, opeing a door or parking lot it’s called NFC (Near Field Communication). These chips are most compatible with devices due to they are formatted in NFC Data Exchange Format (NDEF) and implemented standards published by NFC forum. Their content can be encrypted and some examples are NTAG212, NTAG213, NTAG215 y NTAG216. MIFARE is the NXP Semiconductors-owned trademark and it covers proprietary technologies based upon various levels of the ISO/IEC 14443, incorporating some encryption standards (AES and DES/Triple-DES) and also an older proprietary encryption algorithm.

Conclusion

Access Control is the primary thing for security and is used to protect private and confidential data from attack. Basic access control understanding helps us to manage information security. Four basic models are discussed here. Apart from these four, several models have been developed to increase authenticity, integrity, confidentiality. Another way to provide security is the encryption which uses mathematical algorithm with proper to key to perform operation. Both encryption and access control are used for privacy and to prevent unauthorized users from accessing some object. That data will be in motion so copy or deletion will be possible. With ACL, you can just allow or reject access on a software level not on physical storage. Encryption is used to provide confidentiality of data but data may be access by untrusted entity. Access control is used to provide limited access to the particular entity to particular user as defined by owner.

Note: FIPS (Federal Information Processing Standard) 140-2 is the benchmark for validating the effectiveness of cryptographic hardware. If a product has a FIPS 140-2 certificate you know that it has been tested and formally validated by the U.S. and Canadian Governments.
What is the difference between FIPS 140-2 and FIPS 197 certification? FIPS 197 certification looks at the hardware encryption algorithms used to protect the data. FIPS 140-2 is the next, more advanced level of certification. FIPS 140-2 includes a rigorous analysis of the product's physical properties.
FIPS 140-2 requires that any hardware or software cryptographic module implements algorithms from an approved list. The FIPS validated algorithms cover symmetric and asymmetric encryption techniques as well as use of hash standards and message authentication

References

G.Wang,Q.Liu,J.Wu “Hierarchical attribute-based encryption for fine-grained access control in cloud storage services”2010

M.Green,G.Ateniese “Identity-based proxy re-encryption”2007

GUIDE TO BUILDING AUTOMATION

GUIDE TO BUILDING AUTOMATION

Building automation is monitoring and controlling a building’s systems including: mechanical, security, fire safety, lighting, heating, ventilation, and air conditioning.

Such systems can

• ·         keep building climates within a specified range,
• ·         light rooms according to an occupancy schedule,
• ·         monitor performance and device failures in all systems, and
• ·         alarm facility managers in the event of a malfunction.

Relative to a non-controlled building, a building with a BAS has lower energy and maintenance costs.

There are many components to a building automation system that require a little explaining to understand, and the benefits of installing such a system may not be immediately clear until you understand the mechanisms driving these systems.

That’s why we created this ultimate guide to understanding building automation systems. It’s designed to be an easy read-through, but feel free to use the links below to go directly to a topic that is relevant to your own research.

WHAT IS BUILDING AUTOMATION?

Building automation most broadly refers to creating centralized, networked systems of hardware and software monitors and controls a building’s facility systems (electricity, lighting, plumbing, HVAC, water supply, etc.)

When facilities are monitored and controlled in a seamless fashion, this creates a much more reliable working environment for the building’s tenants. Furthermore, the efficiency introduced through automation allows the building’s facility management team to adopt more sustainable practices and reduce energy costs.

These are the four core functions of a building automation system:

·         To control the building environment

·         To operate systems according to occupancy and energy demand

·         To monitor and correct system performance

·         To alert or sound alarms when needed

At optimal performance levels, an automated building is greener and more user-friendly than a non-controlled building.

A Building Automation System may be denoted as:
An automated system where building services, such as utilities, communicate with each other to exchange digital, analogue or other forms of information, potentially to a central control point.

What Is Meant By ‘Controlled?

A key component in a building automation system is called a controller, which is a small, specialized computer. We will explore exactly how these work in a later section. For now, it’s important to understand the applications of these controllers.

Controllers regulate the performance of various facilities within the building. Traditionally, this includes the following:

·         Mechanical systems

·         Electrical systems

·         Plumbing systems

·         Heating, ventilation and air-conditioning systems

·         Lighting systems

·         Security Systems

·         Surveillance Systems

A more robust building automation system can even control security systems, the fire alarm system and the building’s elevators.

To understand the importance of control, it helps to imagine a much older system, such as an old heating system. Take wood-burning stoves, for example. Anyone heating their buildings through pure woodfire had no way to precisely regulate the temperature, or even the smoke output. Furthermore, fueling that fire was a manual effort.

Fast-forward 150 years: Heating systems can be regulated with intelligent controllers that can set the temperature of a specific room to a precise degree. And it can be set to automatically cool down overnight, when no one is in the building.

The technology that exists today allows buildings to essentially learn from itself. A modern building automation system will monitor the various facilities it controls to understand how to optimize for maximum efficiency. It’s no longer a matter of heating a room to a specific temperature; systems today can learn who enters what rooms at what times so that buildings can adjust to the needs of the tenants, and then conserve energy when none is needed.

There is a growing overlap between the idea of controlling a building and learning from all the data the system collects. That’s why automated buildings are called “smart buildings” or “intelligent buildings.” And they’re getting smarter all the time.

THE EVOLUTION OF SMART BUILDINGS

Kevin Callahan, writing for Automation.com, points to the creation of the incubator thermostat — to keep chicken eggs warm and allow them to hatch — as the origin of smart buildings.

Like most technologies, building automation has advanced just within our lifetimes at a rate that would have baffled facility managers and engineers in, say, the 1950s. Back then, automated buildings relied on pneumatic controls in which compressed air was the medium of exchange for the monitors and controllers in the system.

By the 1980s, microprocessors had become small enough and sufficiently inexpensive that they could be implemented in building automation systems. Moving from compressed air to analog controls to digital controls was nothing short of a revolution. A decade later, open protocols were introduced that allowed the controlled facilities to actually communicate with one another. By the turn of the millennium, wireless technology allowed components to communicate without cable attachments.

An Intelligent Building system may be denoted as:

An automated system where building services and corporate processes, communicate with each other to exchange digital, analogue or other forms of information, to a central control point to manage the environment.

Terms to Understand

At first, the terms building automation professionals use look like a big game of alphabet soup. There are acronyms everywhere. Let’s clarify this now: 

Building Management System (BMS) and Building Control System (BCS) — These are more general terms for systems that control a building’s facilities, although they are not necessarily automation systems.

Building Automation System (BAS) — A BAS is a subset of the management and control systems above and can be a part of the larger BMS or BCS. That said, building management and building automation have so thoroughly overlapped in recent years that it’s understandable people would use those terms interchangeably.

Energy Management System (EMS) and Energy Management Control System (EMCS)— These are systems that specifically deal with energy consumption, metering, etc. There is enough overlap between what a BAS does and what an EMS does that we can consider these synonymous.

Direct Digital Control (DDC) — This is the innovation that was brought about by small, affordable microprocessors in the ‘80s. DDC is the method by which the components of a digital system communicate.

Application Programming Interface (API) — This is a term common in computer programing. It describes the code that defines how two or more pieces of software communicate with one another.

What makes the terminology particularly complicated is that the technology evolves so quickly that it’s hard to know at what point a new term needs to be applied. Then, you also have professionals in different countries using different terms but still having to communicate with one another. Just be prepared for the terminology to be in a state of flux.

HOW DO BUILDING AUTOMATION SYSTEMS WORK?

Basic BAS have five essential components:

Input devices / Sensors — Devices that measure values such as CO2 output, temperature, humidity, daylight or even room occupancy.

Controllers — These are the brains of the systems. Controllers take data from the collectors and decide how the system will respond.

Output devices — These carry out the commands from the controller. Example devices are relays and actuators.

Communications protocols — Think of these as the language spoken among the components of the BAS. A popular example of a communications protocol is BACnet.

Dashboard or user interface — These are the screens or interfaces humans use to interact with the BAS. The dashboard is where building data are reported.

What a BAS Can Do

·         It can set up the lighting and HVAC systems to operate on a schedule that makes those systems both more intelligent and more efficient.

·         It can get the various components and facilities within a building to coordinate and work together toward greater overall efficiency.

·         It can optimize the flow of incoming outside air to regulate freshness, temperature and comfort inside the building.

·         It can tell you when an HVAC unit is running in both heating and cooling helping to reduce utility costs.

·         It can know when an emergency such as a fire breaks out and turn off any facilities that could endanger building occupants.

·         It can detect a problem with one of the building’s facilities — such as, for example, an elevator getting stuck with people inside — and send an instant message or an email to the building’s facility manager to alert him/her of the problem.

·         It can identify who and when someone is entering and leaving a building

·         It can turn a camera on a begin recording when activity takes place – and send an alert and direct camera feed to the security team and facility manager.

·         Are there other functions that address clear pain points for building owners / facility managers?

The Role of Controllers

Controllers are the brains of the BAS, so they require a little more exploration. As mentioned above, the advent of direct digital control modules opened up a whole universe of possibilities for automating buildings.

A digital controller can receive input data, apply logic (an algorithm, just as Google does with search data) to that information, then send out a command based on what information was processed. This is best illustrated through the basic three-part DDC loop:

1.   Let’s say a sensor detects an increase in temperature in a company’s board room when the room is known to be unoccupied.

2.   The controller will apply logic according to what it knows: That no one is expected in that room, thus there is no demand for additional heat, thus there is no need for that room to warm up. (Note: The algorithm with which a controller processes information is actually far more complex than depicted in this example.) It then sends a command to the heating system to reduce output.

3.   The actual heating unit for the boardroom in question receives that command and dials back its heat output. All of this appears to happen almost instantaneously.

WHY ARE BUILDING AUTOMATION SYSTEMS USEFUL?

 The benefits of building automation are manifold, but the real reasons facility managers adopt building automation systems break down into three broad categories:

·         They save building owners money

·         They allow building occupants to feel more comfortable and be more productive

·         They reduce a building’s environmental impact

Saving Money

The place where a BAS can save a building owner a significant amount of money is in utility bills. A more energy-efficient building simply costs less to run.

An automated building can, for example, learn and begin to predict building and room occupancy, as demonstrated earlier with the heated board room example. If a building can know when the demand for lighting or HVAC facilities will wax and wane, then it can dial back output when demand is lower. Estimated energy savings from simply monitoring occupancy range from 10-30%, which can add up to thousands of dollars saved on utilities each month.

Furthermore, a building can also sync up with the outdoor environment for maximum efficiency. This is most useful during the spring and summer, when there is more daylight (and thus less demand for interior lighting) and when it is warmer outside, allowing the building to leverage natural air circulation for comfort.

Data collection and reporting also makes facility management more cost efficient. In the event of a failure somewhere within the system, this will get reported right on the BAS dashboard, meaning a facility professional doesn’t have to spend time looking for and trying to diagnose the problem.

Finally, optimizing the operations of different building facilities extends the lives of the actual equipment, meaning reduced replacement and maintenance costs.

Typically, facility managers find that the money a BAS saves them will over time offset the installation and implementation of the system itself.

Comfort and Productivity

Smarter control over the building’s internal environment will keep occupants happier, thereby reducing complaints and time spent resolving those complaints. Furthermore, studies have shown that improved ventilation and air quality have a direct impact on a business’s bottom line: Employees take fewer sick days, and greater comfort allows employees to focus on their work, allowing them to increase their individual productivity.

Environmentally Friendly

The key to an automated building’s reduced environmental impact is its energy efficiency. By reducing energy consumption, a BAS can reduce the output of greenhouse gases and improve the building’s indoor air quality, the latter of which ties back into bottom-line concerns about occupant productivity.

Furthermore, an automated building can monitor and thus control waste in facilities such as the plumbing and wastewater systems. By reducing waste through efficiencies, a BAS can leave an even smaller environmental footprint. In addition, a regulatory government agency could collect the BAS’s data to actually validate a building’s energy consumption. This is key if the building’s owner is trying to achieve LEED or some other type of certification.

The fact that everything is integrated into one control system, instead of three separate systems, is a real positive – Arindam Bhadra, Technical Head, SSA Integrate.

Sources

·         http://xinca.com/elements-intelligent-buildings-2734.html

·         http://en.wikipedia.org/wiki/Building_automation

·         https://members.questline.com/presentations/20140403ConsumersEnergyBuildingAutomationSystems.pdf

·         http://highperformancehvac.com/building-automation-systems-hvac-control/

·         http://www.automation.com/portals/industries/building-automation/the-evolution-of-building-automation-systems-bas

·         http://highperformancehvac.com/ddc-systems-direct-digital-controls/

·         http://www.automatedbuildings.com/news/apr14/articles/skyfoundry/140312090000skyfoundry.html

·         http://automatedbuildings.com/news/apr12/articles/8760inc/1203240751018760inc.html

·         http://www.mepc-mn.org/Understanding%20Your%20Utility%20Bill/Benefits%20of%20Building%20Automation%20Systems%20with%20EMS%20Logo.pdf

·         http://www.buildingautomationsystem.org/Benefits-Of-Building-Automation-Systems.html

·         http://www.kmccontrols.com/docs/Building_Sustainability.pdf

Increase of BMS cables sale

Increase of BMS cables sale

The global IBMS market is highly fragmented with the presence of several global and local vendors. Global vendors mostly operate as original equipment manufacturers (OEMs), catering to the requirements of the end-user through distributors/dealers or system integrators. Technical knowledge and ability to customize based on end-user requirement by vendors will hold the key to a strong foothold in the market.

Building management system cables also commonly known as BMS cables, intelligent building cables or automation cables are used to automate all of the systems in place within a building or home. Research suggesting the BMS market will reach $19.25 million by 2023; it’s even more of an opportunity for electrical contractors to capitalize.

The global IBMS market will continue to grow at a healthy pace throughout the forecast period. Apart from energy and cost savings, other important drivers are the degree of flexibility provided by open IBMS solutions, the high degree of productivity it provides, and a higher return on investment along with enhanced security. These factors are attractive to many businesses, thus driving the market growth.

An advance Building Management System can control the safety in homes and offices, monitoring doors and windows for alarm systems and detect floods and fires. Equipment and installations are designed for the control, monitoring and optimization of various functions and services provided in a building that includes: heating, ventilation, air-conditioning, lighting, security systems and the operation of electric / electronic applications. 

A shielded cable that is not grounded does not work effectively. Any disruptions in the path can raise the impedance and lower the shielding effectiveness. Firstly make sure you have a cable with sufficient shielding for the application's needs. In moderately noisy environments, a foil alone may provide adequate protection. screened cable (plural screened cables) Wire for the transmission of electricity or electronic signals, protected by an enclosing web of earthed wire mesh to avoid electromagnetic interference from (or to) other signals. Grounding: a point in contact with the ground, a common return in an electric circuit and a arbitrary point of zero voltage potential. It also provides personal safety and protects the equipment. Control the voltages developed on the ground when the earth-phase short circuit returns through a near or distant source. Provide a stable voltage reference to signals and circuits. Minimize Electromagnetic Emission (EMI) effects.

Shielding: The shield must be connected to the signal reference potential of what is being protected. When there are multiple segments keep them connected, ensuring the same reference potential. The shielding is only efficient when it establishes a low impedance path to the ground. A floating shielding does not protect against interference. The use of non-magnetic metals around conductors does not shield against magnetic fields.

The cabling of the industrial communication systems (Modbus RS485) is different in some ways from the cabling used for power cabling and the electrician may experience some difficulties if he is not an expert in Modbus communication networks. A Modbus RS485 connects a Master device to one or more Slave devices. Henceforth, we shall consider Slave devices to be measuring instruments with serial communication, even if the cabling is similar for all Modbus devices.

Cable Selection

You should consider the following:

·         How many conductors do you need?

A minimum of three conductors, but the shield may be used as the common conductor, so shielded two conductor cable may be used. If you do not use shielded cable, then at least three conductors are required. Some RS-485 devices do not use a common connection, but we recommend always connecting common for reliable performance and to avoid damage due to surges.

·         What wire gauge do you need?

·         For unterminated networks, the current will generally be less than 10 mA and any gauge should work; we recommend #24 AWG to 18 AWG.

·         For terminated networks, the current can be 60 mA or higher, so heavier gauge wire may be needed for very long runs.

·         We recommend #22 to #20 AWG for runs up to 1000 ft. (~300 m).

·         We recommend #20 to #16 AWG for runs up to 4000 ft.(~1200 m).

·         What should the cable impedance and capacitance be?

Cables suitable for use in an RS-485 network should have an impedance of between 100 and 130 ohms, a capacitance between conductors of less than 30 pF per foot (100 pF per meter), and a capacitance between conductors and shield less than 60 pF per foot (200 pF per meter).

·         Do you need shielding?

Because RS-485 is differential, it is less susceptible to interference, so shielding is not always necessary. However, we recommend shielding for long runs and if there is electrically noisy equipment nearby like variable speed drives. If you use shielded cable, connect the shield to earth ground at one end (generally the PC or RS-485 master).

·         Do you need twisted wires?

Yes, especially for non-shielded cable.

·         What voltage rating do you need?

We recommend wire or cable rated for the highest voltage present. So if you are monitoring a 120/208 Vac panel, you should use 300 V rated cable. If you are monitoring a 480Y/277 volt circuit, use 600 V rated cable. If you have the WattNode in a separate enclosure and there is no way the mains wires can contact the Modbus output cable, then you could safely use lower voltage rated cable, such as 150 V or lower. Long runs of 300 V or 600 V rated cable may be expensive, so it may be more economical to use lower voltage rated cable and use a protective jacket in the regions where the cable is in the vicinity of dangerous voltages.

·         Can you run the RS-485 network cable adjacent to or in the same conduit with mains wires?

We strongly recommend against this. There may be interference from the high voltages and currents present on the mains wires, and if there is any insulation fault, arcing, etc. on the mains wires, it could put dangerous voltages on the low-voltage RS-485 network cable.

Most modern buildings now incorporate some form of BMS, focusing primarily on energy efficiency and saving costs. Whether that’s through proximity sensor lighting, climate control, door entry or security, they all work to achieve the same goal.

Efficient lighting control in a BMS system is just one way of reducing energy and saving costs for building owners. Using BMS, lighting can be automatically adjusted, depending on natural light detected or amount of people in the building. These cables are available in Low Smoke Halogen Free (LSHF), meaning they give off minimal smoke and toxic fumes. This is ideal for installation in public buildings such as schools, hospitals or airports where evacuation may be difficult in the event of a fire.

Unlike what happens in many energy distribution systems, the manner in which the devices are connected in parallel is important. The RS-485 system used for Modbus communication provides a main cable (Bus or backbone), to which all the devices have to be connected with branches (also known as stubs) that are as short as possible. The branches must be no longer than 1200 mtr.

Maximum distance and maximum number of devices. The main cable must be no longer than 700 m! This distance does not include the branches (which must nevertheless be short). The maximum number of devices that can be connected to a main cable is 32, including the Master.

In order to increase the extent of the Modbus network, repeaters can be used; and signal amplifying and regenerating devices provided with two communication ports that transfer to each what they receive from the other.

The cable shield must be earthed only in one point. Normally, this connection is made at one end of the main cable.

In order to avoid signal reflections, a 120 Ohm termination resistance must be fitted on each end of the main cable. The end resistance must be used only at the ends of the main cable. If the total length of the main cable is less than 50 m termination resistances can be avoided at the ends of the main cable.

Fire safety is another major reason why owners may consider installing a BMS system into their building. High performance fire survival cables provide an excellent solution for connecting BMS with fire systems. The data and coaxial ranges are designed to carry on functioning in the event of a fire and provide vital signals to voice alarm, CCTV and allow systems to be shut down in an orderly fashion. Meeting specific fire resistance requirements.