Power Systems POWER SYSTEMS TOPICS 106

Digital Communications in Electrical Generation Systems

The stakeholder team should ask these By Today, electrical generation systems are rarely used as isolated, stand- questions: Bill Gross Senior Staff Engineer– alone systems. More often, they s 7HO NEEDS TO BE PART OF THIS DISCUSSION Electronics Software need to communicate with peripheral Participants could include information +/(,%2 0OWER 3YSTEMS devices, other generation systems, technology, building maintenance, Nicole Dierksheide building management systems or production management and energy Product Manager–Controls !43 +/(,%2 0OWER remote monitors. As a result, there management personnel. Systems are a number of technologies used s 7HAT EXISTING SYSTEMS NEED TO COMMUNICATE to enable communication between WITH THE ELECTRICAL GENERATION SYSTEM electrical generation systems and other equipment. If you’re involved in s 7HAT INFORMATIONSTATUS INDICATION DO specifying, installing or maintaining you need to gather from the electrical electrical generation systems, you’ll GENERATION SYSTEM 7HAT EXACT DATA DO YOU NEED COMMUNICATED find it helpful to understand how these communication technologies work to s 7HERE DOES THIS DATA NEED TO BE SENT (OW meet your needs and the requirements long is the distance from electrical generation of the building. SYSTEM TO END DEVICE It’s important to involve all stakeholders s 7HAT IS THE COMMUNICATION HARDWARE AND when you discuss integrating the existing protocol employed by the building systems with the electrical generation management system devices (or other systems) that will connect to the electrical system. Mutual agreement on the needs GENERATION SYSTEM 7HAT HARDWARE AND and desired functionality will ensure protocol should be specified to operate with a system that operates as required. THE EXISTING SYSTEMS Specifying the correct communication technologies at the beginning can save This paper provides information on digital you and your clients hours of frustration communication systems used in electrical as you try to make mismatched systems generation systems that will help you understand work or have installation delayed while why the answers to these questions are so IMPORTANT 7HEN THE STAKEHOLDER TEAM you order the correct parts. incorporates this knowledge and answers the questions, they’ll be able to develop a comprehensive, well-thought-out electrical generation system specification, and avoid pitfalls during installation and use.

WHAT COMPRISES A COMMUNICATION composed of digital circuitry, which meets SYSTEM WITHIN AN ELECTRICAL precise timing and power requirements put forth GENERATION SYSTEM? by an international standards committee. A communication system consists of two Because of this standardization, the hardware separate, independent components: the component of the communication system tends hardware and the protocol. You can think of the to be straightforward. An everyday example of hardware as the physical devices – things you communication hardware would be a USB can touch – and the protocol as the software that (Universal Serial Bus) cable and connectors allows data to flow between the hardware. between a PC and a printer. In a human model, the hardware elements are The protocol, or language, used to communicate the people and the protocol is the language. See over hardware is open to a much greater degree Figure 1. Usually, the communication challenge of variation. There can be multiple protocols (or for humans is the potential for differences in languages) that communicate through a given language. Each person must follow certain type of hardware. Additionally, some protocols grammatical rules for the communication to be are created as industry standards. Similar to the meaningful. Speed can also be a factor. Most of hardware standards referenced above, protocol us have experienced listening to someone who is standards define the manner in which the hard to follow because they talk too fast, or language is composed, so two devices someone else who tries our patience because connected through the hardware can talk to each they talk so dreadfully slow. Similarly, comm- other if using the same protocol. If a protocol is unication networks can experience similar issues not defined by an industry standard, then it is that are like a conversation being interrupted by considered proprietary. Information about others, or the person you’re talking with going off proprietary protocols is not usually widely on a tangent and losing the main point of the shared. Only other developers who know its conversation. Additionally, if there is great details can develop products that will be able to enough distance between humans, then communicate through the proprietary protocol. additional hardware is required and if the hardware cannot connect, such as through a The use of a USB memory stick is an example of telephone, the language cannot be transmitted. a standard protocol. Think of plugging in a These are the standards in human memory stick from one computer to another. communication. Each computer can recognize it because it adheres to a standard. An example of a PROTOCOL proprietary protocol is the in-vehicle Language communication system used by mechanics’ diagnostic computers to service your automobile. The communication between the HARDWARE engine computer and the other car components Air HARDWARE HARDWARE is via proprietary protocols unique to each auto Human 1 Human 2 Figure 1. manufacturer. Human Communication Model 7HILE PREPARING AN ELECTRICAL GENERATION SYSTEM Communication between electronic devices is specification, it is vital to gather communication like communication between people – with hardware and protocol information for each similar complexities and issues. In a device or system that must communicate with communication system, the hardware is the new electrical generation system.

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The collection of this hardware and protocol what is transmitted on each connection point. data will assure appropriate system functionality. 7HEN SELECTING THE CABLING IT MUST BE DElNED AS

It is also important to identify any adapters that 23 TWISTED PAIR +/(,%2® Power Systems may be necessary to convert from one hardware recommends Belden as a high-quality cable ANDOR PROTOCOL TO ANOTHER 4HE FOLLOWING SELECTION 23 DOES NOT DElNE THE PHYSICAL sections describe common communication characteristics of the connection points on each HARDWARENETWORKS AND PROTOCOLS USED IN end. A Euroblock connector is typically used electrical generation systems. ON +/(,%2 GENERATION SYSTEMS ! %UROBLOCK COMMUNICATIONS HARDWARE AND PROTOCOLS USED IN connector is a pluggable terminal block that uses ELECTRIC GENERATION SYSTEMS screw terminals to clamp connecting wires. It provides a quick, convenient way to connect and COMMON disconnect electronic devices. HARDWARE PROTOCOL CONNECTOR CABLE APPLICATIONS !N IMPORTANT CHARACTERISTIC OF 23 IS THE

Modbus RTU Generation NEED FOR A TERMINATING RESISTOR 7ITHOUT A Twisted-Pair system controller RS-485 Euroblock (Belden) to external terminating resistor, messages can interfere with Rbus systems each other. A terminating resistor ensures that J1939 Engine to the communicated message stops at the last generator Cable with ADEC/MDEC 9-pin controller, device rather than reflecting or bouncing back CAN connector on D-subminiature generator to SmartCraft end and interfering with the next message sent. The external devices NMEA 2000 (gauges, I/O, etc.) generation system specification must detail the IP special steps required to ensure proper operation Modbus TCP WHEN EMPLOYING AN 23 SERIAL NETWORK Cable with Building RJ-45 Ethernet SNMP RJ-45 plug and management receptacle RS-485 CONSIDERATIONS Cat 5 cable systems BACnet s 23 CAN BE A LOWER COST HARDWARE CHOICE LonWorks compared to other options if the distance Generator to PC Type B Cable with Device Mode for configuration IS NOT SIGNIlCANT "ECAUSE 23 REQUIRES A receptacle Type B plug or data download twisted-pair cable, it can become costly to run USB Generator to flash Type A Cable with the cable great distances, especially if it needs Host Mode drive to download receptacle Type A plug or upload data to be encased in conduit. s 23 CAN FUNCTION IN DISTANCES UP TO RS-485 METERS FEET RS-485 SERIAL NETWORKS (HARDWARE) s 23 WORKS WELL IN ELECTRICALLY NOISY 4HE 23 STANDARD DElNES A PHYSICAL environments. connection for serial networks. It should not s 23 OFFERS RELATIVELY LOWER COMMUNICATION BE CONFUSED WITH 23 ANOTHER SERIAL speeds compared to other choices. This is network standard that was typically deployed not an issue in most situations, but could on computers in the past. Developed in the become noticeable if large amounts of data EARLY S 23 IS STILL EXTREMELY POPULAR are being transferred. in industrial communication products today. MODBUS RTU (PROTOCOL) 4HE 23 STANDARD DElNES THE PHYSICAL Figure 2. manner in which the devices are connected -ODBUS 245 REMOTE TERMINAL UNIT IS A SERIAL Euroblock Connector as twisted-pair with a specific configuration of communication protocol developed in the late

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S )T COMMUNICATES OVER THE 23 through its use in engines. CAN is the standard hardware layer and is the most common network system for the automotive industry and is implementation of Modbus. It can be used used by almost all ECMs (engine control module). to communicate with building management #!. IS SIMILAR TO 23 IN THAT IT DElNES THE systems, such as SCADA, and other systems physical manner (voltage, current, number that support the protocol. of connectors) in which the devices are 4HE -ODBUS 245 PROTOCOL SPECIlES THAT AN connected. CAN does not deﬁne the mechanical individual device on the network must be the characteristics of the connection points on each primary (master) device while all other devices end. A 9-pin, D-subminiature-style connector are secondary (slave). The primary is the only is often utilized, but other connectors may be device that can initiate communication activity. EMPLOYED +/(,%2 OFTEN USES 2* CONNECTORS All secondary devices react according to the for CAN communication. initiation of the primary. !NOTHER SIMILARITY BETWEEN #!. AND 23 that should not be overlooked is the need for a terminating resistor to ensure the communicated

Slave Slave message stops at the last device rather than reﬂecting or bouncing back and interfering with the next message sent. Modbus RTU On generation systems, CAN is used to Modbus RTU Modbus communicate not only with the engine but also WITH REMOTE INPUTOUTPUT BOARDS AND EXTERNAL

Master Master GAUGES +/(,%2 TYPICALLY USES A DEDICATED #!. Modbus RTU Modbus RTU network for the ECM and a separate CAN network for all other communication to keep the “chatter” Slave Slave down on the network with the ECM. Figure 3. CAN CONSIDERATIONS RS-485 Conﬁguration Diagram s #!. IS A RELATIVELY LOWER COST HARDWARE RBUS (PROTOCOL) choice due to the common components and 2BUS IS A +/(,%2® proprietary protocol short cable distances. developed primarily for use with residential and s #!. FUNCTIONS AT A RELATIVELY SHORTER light commercial products. It communicates DISTANCE METERS FEET THAN OVER THE 23 HARDWARE LAYER AND CREATES A other options. HOLISTIC SOLUTION AMONG +/(,%2 GENERATORS s #!. PROVIDES EXCELLENT IMMUNITY TO transfer switches, programmable interface electrically noisy environments. module, load control modules and similar devices. Because it is proprietary, it does not s #!.S MULTI NODE ARCHITECTURE AS OPPOSED allow communication with non-proprietary to master-slave) allows devices to systems. communicate without a single point of failure. CAN s #!. ALLOWS FOR GOOD Figure 4. communication speeds. CAN NETWORKS (HARDWARE) 9-Pin D-Subminiature J1939 (PROTOCOL) Connector CAN (controller area network), also called CANbus, is a communication network that The most common protocol used with CAN is found its way into the power generation market * A STANDARD PROTOCOL SPECIlED BY THE

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Society of Automotive Engineers (SAE). This assigned a unique MAC (media access control) protocol is found on the network running in address by the manufacturer. many cars throughout the world. It is also In addition, while Ethernet makes global used by the majority of generator engine accessibility to information possible, it also manufacturers. creates security concerns. As such, many ADEC/MDEC (PROTOCOL) businesses deploy additional security measures, !$%#-$%# ADVANCED DIESEL ENGINE CONTROL such as firewalls, that prevent external devices (MTU diesel electronic control) are proprietary from accessing internal systems. These additional CAN protocols owned by manufacturer MTU security measures, along with the fact that every and used for communications with its ECMs. device must have a unique ID, create technical SMARTCRAFT (PROTOCOL) challenges when deploying an Ethernet solution. In most cases, the company’s IT (information SmartCraft is a CAN protocol developed by technology) group is involved to help configure Mercury Marine for use in boat systems. Boats and set up the system. employ a wide variety of devices, including engine gauges, fire detections systems and ETHERNET CONSIDERATIONS radar gear. Because of this, the SmartCraft s %THERNET CAN BE COSTLIER THAN OTHER protocol has been designed to gracefully networking methods due to the additional accommodate identification, addition and equipment, such as routers, that it requires. removal of devices on the bus. s %THERNET HARDWARE APPLICATIONS OFTEN REQUIRE NMEA 2000 (PROTOCOL) involvement of IT experts to get the devices This protocol was developed by the National configured and communicating on the Marine Electronics Association for use in INTERNET INTRANET OR ,!. ,OCAL !REA .ETWORK marine products. It is used in the marine s %THERNET SUPPORTS VERY LARGE NETWORKS AND industry as an alternative to the SmartCraft long distances. PROTOCOL AND * s )T INTEGRATES WELL WITH COMMON NETWORKING ETHERNET infrastructure, eliminating the need to be local. ETHERNET NETWORKS s %THERNET ALLOWS FOR VERY HIGH COMMUNICATION (HARDWARE) speeds. Almost everyone is familiar with s %THERNETS MULTI NODE ARCHITECTURE AS Ethernet; it is one of the most opposed to master-slave) allows devices to common ways to access the Internet. communicate without a single point of failure. The physical manner can vary; INTERNET PROTOCOL (PROTOCOL) for example, as a wired Ethernet The most common Ethernet protocol is the connector into a router or a wireless Internet Protocol (IP). It assigns each device a Figure 5. CONNECTION VIA 7I &I -OST GENERATION SYSTEMS Cat 5 Cable & RJ-45 second address called an IP address. Unlike MAC Connector that employ Ethernet in their communication addresses, which are independent of physical solutions use a connector commonly referred device network location, IP addresses follow a TO AS 2* REMOTE JACK ON THE END OF A #AT numbering hierarchy that corresponds to device #ATEGORY CABLE locations within the network structure. Therefore, 7HILE THE %THERNET NETWORK IS HIGHLY SCALABLE while a device’s MAC address remains fixed, its IP to handle many devices, it does require each address will change if the device is plugged into a device to have a unique ID. Each device is different segment of a network. Network managers

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ALLOCATE A BLOCK OF )0 ADDRESSES TO EACH ,!. IN a network and an individual IP address to each

DEVICE WITHIN A ,!. Modbus RTU A device’s address may be programmed

manually (in which case the address is called SNMP a static IP address) or automatically using a PROTOCOL CALLED $YNAMIC (OST #ONlGURATION SNMP Modbus RTU 0ROTOCOL $(#0 4HIS IS A VERY IMPORTANT detail when writing a generation system speciﬁcation. If dynamic IP addresses are used for devices, it may be difﬁcult for digital communication systems to discover the Modbus RTU device. Typically, the device will be associated with an IP address. If the Internet service BACnet provider changes the IP address through

$(#0 INBOUND CONNECTIONS WITH THE DEVICE BACnet can be lost. Modbus RTU MODBUS TCP (PROTOCOL) Figure 7. Modbus TCP (transmission control protocol) RS-485 Ethernet BACnet Conﬁguration Diagram communication over Ethernet is a protocol that generally uses Modbus-to-Ethernet converters SNMP (PROTOCOL) to create a Modbus-type network to enable remote monitoring or overcome limitations SNMP (simple network management protocol) is INHERENT WITH -ODBUS 245 SUCH AS DISTANCE an Ethernet protocol typically used by building or the number of master devices on a bus. management systems to monitor for certain There can be numerous masters requesting messages from devices. In the case of generation information from the secondary device. systems, SNMP is monitoring for any events that the system may send, such as a fault from

Modbus RTU the generator. Once the event is sent out via the protocol, it is “trapped” by, and used to generate an alert through, the management system. Modbus TCP BACNET (PROTOCOL)

Modbus TCP BACnet (building automation and control networks) is a communication protocol typically

Modbus RTU Modbus TCP Modbus TCP used by building management systems to monitor for certain messages from devices. It is similar Modbus TCP to SNMP in that it can be used over a variety of

Modbus RTU RTU Modbus hardware layers, including Ethernet. ATS GENSET LONWORKS (PROTOCOL) ,ON7ORKS LOCAL OPERATION NETWORK IS A communication protocol typically used by building management systems to monitor for certain Figure 6. messages from devices. It is a rival of BACnet and RS-485 Ethernet SNMP Conﬁguration Diagram

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is focused specifically on the needs of control applications. It has been emerging over the last few years but is still used relatively infrequently. USB USB COMMUNICATION (HARDWARE) Given the proliferation of USB (Universal Serial Bus) applications for personal computers, it’s natural to see it used within electrical generation systems – mostly to provide access between a computer and the generation system. This access could also include mass storage devices (e.g., flash drives) for transferring files, such as log files, event files and configuration files, to and from the system. USB CONSIDERATIONS s 53" IS A STANDARD IN COMMON USE s 53" PROVIDES VERY FAST Figure 8. USB Configuration Diagram communication speeds. s 53" OPERATES AT RELATIVELY SHORTER DISTANCES than other options. USB HOST MODE s 53" IS LIMITED TO COMMUNICATION BETWEEN Generator controllers that communicate via two devices only, not a network of USB host mode can be reprogrammed using multiple devices. a flash drive (also called a thumb drive or USB USB DEVICE MODE memory stick) or can log data to a flash drive. Type A connectors are used for USB host Generator controllers will communicate via mode. USB device mode with PCs via a program like +/(,%2 GENERATOR CONTROLLERS SUPPORTING 53" +/(,%2® SiteTech, which is set-up software available only to Kohler-certified technicians. host mode include: The USB connector on the controller allows s !$# !$#$ n -ARINE GENERATOR technicians to interface with SiteTech; Type controllers B connectors are used for USB device mode communications. +/(,%2 GENERATOR CONTROLLERS SUPPORTING 53" device mode include: s $%# n )NDUSTRIAL GENERATOR CONTROLLER s 2$# $# 2$# $# n 2ESIDENTIAL Type B Type B Type B Type A Type A MICRO MINI Plug Receptacle Plug generator controllers Plug Plug

s !$# !$#$ n -ARINE GENERATOR Figure 9. controllers Various USB Connectors

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CONCLUSION There is a large variety of hardware and protocols available today for generator and building systems. The key to choosing the best equipment and systems for your application involves preparation with key stakeholders. Individuals responsible for specifying electrical generation systems must involve all stakeholders to catalog existing devices and systems that need to communicate with the new electrical generation system. These devices may include building management, energy management, security production or other systems. The stakeholders may include information technology experts, building managers, production engineers or other professionals responsible for operations. Using this paper as a guide, this team will develop a thorough description of the current systems’ hardware and protocol used by all equipment that will be connected to the generator system. Then, stakeholders should determine how these systems need to communicate, what data must be collected and where all devices are LOCATED 7ITH THIS KNOWLEDGE A COMPREHENSIVE speciﬁcation can be developed detailing the desired electrical generation system including digital communication hardware and protocol. $O THESE SYSTEMS RELY ON 23 #!. AND OR %THERNET NETWORKS 7HICH PROTOCOLS ARE EMPLOYED ON WHICH SYSTEMS 7HAT IS THE DISTANCE BETWEEN DEVICES !NSWERS TO THESE questions and comprehensive, upfront planning will result in better generator system solutions – AND ULTIMATELY HAPPIER CUSTOMERS +/(,%2 distributors have the expertise to ensure that your electrical generation system speciﬁcation and purchase results in the desired functionality.

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ABOUT THE AUTHORS Bill Gross is a Senior Staff Engineer Nicole Dierksheide is a Product with Kohler Power Systems–Americas. Manager with Kohler Power Systems– He holds a Bachelor of Arts in liberal Americas. She holds a Bachelor of studies concentrated on chemistry, Science in electrical engineering from physics and math from Indiana University the University of Arizona. Nicole has and a Master of Arts in chemistry from been with Kohler since 2010 and Ball State University. Bill has been with specializes in statutory controls, digital Kohler since 2007 and specializes in communication and automatic transfer remote monitoring, PC applications switches for Kohler Power Systems. and embedded controllers for Kohler Power Systems. He developed the initial OnCue® product for Kohler, enabling homeowners to monitor their residential generator set over the Internet.

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