The PL1000T, when configured to provide the “J1939 Bridge” functionality, will join two independent J1939 networks into a single J1939 network.
Illustration 1 shows a complete “J1939 Bridge” network. The two independent J1939 networks are joined through the PL1000T. When configured to provide the “J1939 Bridge” functionality, the PL1000T ECM functions as a repeater between the two J1939 networks. The PL1000T will forward any incoming J1939 data to the bridged network, regardless of message format or data content.
All J1939 messages on Network 1 will be relayed to Network 2, and all J1939 messages on Network 2 will be relayed to Network 1. Each message being relayed will be presented entirely on the destination J1939 Network. Each message will appear to have originated on the destination J1939 network.
An example application for implementation of the “J1939 Bridge” feature is on a marine vessel. In some larger marine vessels the engines are typically located a significant distance from the bridge or engine monitoring station. Typical CAN data link physical network specifications require the wiring be limited to a total distance of no greater than 40 m.
The “J1939 Bridge” feature of the PL1000T can provide two physical networks while maintaining a single logical network, which will allow wiring on each CAN network to run a total of 40 m (131 ft) each. With an available 40 m (131 ft) on each physical link, the total logical CAN network is now limited by the total of 80 m (262 ft).
In this particular example the PL1000T would be positioned mid distant between the engine room and the bridge or monitoring station.
The PL1000T, when configured to provide the CAN Extension Bridge functionality, will join two CAN networks into a single network. While similar in function to the “J1939 Bridge” feature, the CAN Extension Bridge feature allows a much longer span and requires two PL1000Ts.
Illustration 2 shows a complete CAN “Extension Bridge” network. “Network 1” is logically connected to “Network 2” through the RS-485 network that is used between the two PL1000Ts.
There can also be a logical connection between Network 3 and Network 4 through the same RS-485 Network and PL1000Ts. When configured to provide the “CAN Extension Bridge” functionality, each of the PL1000Ts will “multiplexe” and “de-multiplexe” the J1939 communications over the RS-485 network.
The two new logical networks share the RS-485 connection. The data from CAN networks 1 and 2, is not available on networks 3 or 4. The reverse is also true. Each message is being relayed on the two independent logical networks.
An example application for implementation of the “CAN Extension Bridge” feature is on a marine vessel. In some larger marine vessels the engines are typically located a significant distance from the bridge or engine monitoring station. Typical CAN data link physical network specifications require the wiring be limited to a total distance of no greater than 40 m (131 ft).
The “CAN Extension Bridge” feature can accommodate four physical networks while maintaining two independent logical networks. The “CAN Extension Bridge” feature will allow wiring on each original CAN network to run a total of 40 m (131 ft) each.
The information from each of these networks can then be passed along the RS-485 network between the two PL1000Ts for a distance up to 305 m (1000 ft).
One of the PL1000Ts in this example would be positioned within 40 m (131 ft) of up to two CAN networks in the bridge or engine monitoring station, and the other PL1000T would be positioned within 40 m (131 ft) of up to two CAN networks in the engine room.
These two PL1000Ts would then be connected by the RS-485 network not to exceed 305 m (1000 ft). Messages would then be relayed across the two logical CAN networks.
“Multi-plexing” two J1939 networks over the RS-485 communication and link between the two PL1000T devices, can restrict the normal bandwidth of a J1939 network. The restriction can be as much as 40 percent. If intermittent data loss is experienced, the date link loading should be analyzed.
The Engine Vision Display is a computerized monitoring system that is used in order to display engine information. The engine information includes temperatures, pressures and levels concurrently up to three engines.
Illustration 3 shows an example integration of the PL1000T into a system as an “Engine Vision Interface Module”.
The PL1000T, when configured to provide the EVIM feature, translates the EVIM data requests to the engine control. The PL1000T then translates the engine data responses back to the EVIM.
The PL1000T is a direct functional replacement for the existing 225-0774 System Communication Module Gp. However, the PL1000T will require some different system wiring and system integration considerations.
This manual is intended to address the EVIM communications capability of the PL1000T. For specific information related to installation, operation, and troubleshooting of the “Engine Vision Display”, refer to the Service Manual, SENR5002.
The PL1000T, when configured to provide the GPSIM feature, receives “Global Positioning System” (GPS) information from the “NMEA-183” sensing module. The PL1000T transmits the GPS information on the Cat Datalink and J1939 networks.
Illustration 4 shows an example integration of the PL1000T into a system as a “Global Positioning System Interface Module”.
This PL1000T feature is designed as a direct functional replacement of the existing 130-6191 System Communication Module Gp. However, The PL1000T will require some changes to the system wiring and system integration considerations.
This manual is intended to address the GPSIM communications capability of the PL1000T, which is typically used with the “Engine Vision Display”. For specific information related to installation, operation, and troubleshooting of the “Engine Vision Display” refer to the Service Manual, SENR5002.
The PL1000T can be configured to transmit the full content of one protocol inside the envelope of another protocol.
All messages on the Cat Datalink are received by the PL1000T. The entire message is placed into a special tunneling J1939 message. The messages are transmitted over the J1939 network. The “CDL Tunnel” feature is designed for use with the Caterpillar 3500B Series II Engines. The “CDL Tunnel” is a replacement for the previous 171-4454 Interface Module Gp.
Note: Each engine will require PL1000T for translating the “CDL Tunnel” messages to Cat Datalink. No more than three PL1000Ts can be connected to the same Cat Datalink network.
The PL1000T, when configured to provide the “Sea Water Module Interface” (SWMI) feature, receives water temperature and water depth information from the “NMEA-183” sensing module. The PL1000T transmits the information on the Cat Datalink and J1939 networks.
Illustration 6 shows an example integration of the PL1000T into a system that is designed as an SWMI.
This manual is intended to address the SWMI interface capability of the PL1000T. Refer to the documentation of the Caterpillar display for specific information for installation, operation, and troubleshooting the ability to display the “Sea Water Module” information.
“CDL Boost” is available with the PL1000T. “CDL Boost” enables a customer to extend the lengths of CDL wire harnesses. The lengths of CDL wire harnesses can extend to a maximum length of 300 m (1000 ft). Data integrity will be maintained.
Note: In order to enable CDL boost for the 256-7511 Communication Electronic Control Module v4, pin 7 of the PL1000T must be grounded. Cat ET will show a status parameter that informs the user if CDL boost is enabled or disabled.
The PL1000T, when configured to provide the Customer Communications Module Interface feature, is designed to communicate with Caterpillar M5X and M50 protocol commands. Communication is accomplished with the use of Cat Datalink and J1939 networks. Either single parameter read/write commands are used or broadcast list commands are used. Refer to the M5X programming section or the M50 programming section of this document for information about the communication protocols.
The CCM feature allows the PL1000T to provide a communications link between the ECM and a host device. The host device can be a:
- Programmable Logic Control (PLC)
- Personal Computer (PC)
- RS-232 Capable Device
The CCM feature requires special instructions in order to interface with the PL1000T that use M5X or M50 protocols. The protocols provide “Instruction Identifiers” (IID). The “Instruction Identifiers” can be used in order to program the PL1000T for monitoring and control of the desired engine parameters.
The requested parameters will be gathered by the PL1000T from the engine control. The requested parameters will be presented over the M5X or M50 protocol link based upon the information that is provided with the instruction identifier.
Refer to the M5X programming section or the M50 programming section of this manual for information about the communications requirements. Each programming section also describes methods of using the instruction identifiers for M5X or M50 protocol. The programming section of this manual does not address the engine-specific parameters that are necessary for monitoring engines. The parameters that are specific to the engine and the supported M5X or M50 protocol, should be referenced in the “System Operation Test and Adjust” manual for the specific engine.
Refer to the “System Operation Test and Adjust” manual for a specific engine and information about the parameters specific to the engine. The “System Operation Test and Adjust” also describes the supported M5X or M50 protocol.
The PL1000T is shipped from the factory with default settings to facilitate M5X and M50 protocols as described in Table 1.
If there is a need to modify the communications characteristics of the “Com 1” serial port, refer to the “Configuration” section of this document. RS-232 communication is available at baud rates up to 38,400 bps. RS-485 communications are not available at this time.
The PL1000T is compatible with the following applications:
CCM PC – An application that provides an interface through the PL1000T configured serial port. Parameters may be viewed using the M5X or M50 protocol, but the serial port configuration cannot be modified using the CCM-PC software.
EERP1000 Caterpillar Communications Toolkit – The Caterpillar Communications Toolkit provides the ability for configuration of the PL1000T ports and protocols.
Caterpillar Electronic Technician – The Caterpillar Electronic Technician (Cat ET) is a dealer service tool that provides the same functionality as the Caterpillar Communications Toolkit with respect to the PL1000T. However the PL1000T provides a greater range of capabilities for the electronic engine controls than what may exist in the customers system. If there is trouble with the system and the electronic engine controller is suspected, contact the local dealer.
The PL1000T communicates with the host via standard RS-232 serial link. The serial data link uses the M5X or M50 protocol to transfer data over this standard RS-232 hardware communications link. The M5X and M50 protocol instruction identifiers host equipment can then use the engine parameters collected to monitor engine performance, parameters reads, and writes allowing the host equipment to exercise some control of the engine via the PL1000T.
The PL1000T supports a maximum of 16 broadcast lists, and each list can consist of a maximum of 8 “Parameter Identification’s” (PIDs). A broadcast list may contain PIDs from different engine controls, but the PL1000T can only have eight individual electronic engine controls connected at the same time.
The PIDs are connected by the CDL. The PIDs are sent to a remote computer system through the RS-232 connection that uses the M5X protocol or the M50 protocol. Most Caterpillar electronic systems that are designed for use with the PL1000T can provide a maximum of 50 PIDs per second.
However that speed may vary depending upon baud rate and the type electronic module connected. For example, a cellular phone connection at 2400 baud rate would reduce the throughput to only 29 PIDs per second. Other modules on the CDL utilize complex systems that can reduce the number of PIDs managed to less than 40 PIDs per second.
The following suggestions will help obtain the maximum throughput possible.
- Request stable PIDs less frequently
- Configure broadcast lists that retrieve data such as hour meter, atmospheric pressure, or diagnostics at less frequent rates that parameters such as engine speed or oil pressure.
- Requesting stable PIDs less frequently will optimize the capability of the data transfer and minimize communications loading.
All command messages must be sent to the PL1000T in ASCII format, and the response will also be in ASCII format. See Table 1. The broadcast lists can be programmed in either ASCII or binary format.
The PL1000T may be connected directly to the host equipment. The PL1000T may also be connected to the equipment by using modems. The initialization procedure depends on the type of connection. The correct initialization procedure is necessary for proper communication between the PL1000T and the equipment.
When modems are installed between the PL1000T and the host equipment, the complexity of the communications network is increased. The RS-232 ports must be set to the proper parameters for communication on the following equipment: host equipment, modems, and PL1000T. The phone line ports of the modems must be compatible. To connect the modems, consult the manufacturers instructions.
If the PL1000T is connected to other “Data Terminal Equipment” (DTE) devices, then a “Null Modem” cable or an adapter is required. A personal computer is an example of a DTE device.
The “Transmit” line of the PL1000T must be connected to the “Receive” line of the personal computer or other DTE device. Also, the “Transmit” line of the personal computer or other DTE device must be connected to the “Receive” line of the PL1000T. The wiring configuration that is discussed here, is commonly referred to as “Crossover” or “Null Modem” wiring.
Direct connections with the PL1000T can be verified with the use of a serial ASCII terminal program. Many terminal programs are commercially available, such as Procomm Plus. However, for this example, a terminal program will be used that is available with Microsoft Windows. The terminal program that is available with Microsoft Windows is called Hyperterminal.
Refer to the “Hyperterminal” section of this document for usage information.
The PL1000T communicates with the use of the M5X protocol or M50 protocol. The protocol consists of single parameter, composite, and broadcast list commands.
If any of the 16 broadcast lists, events, or diagnostic messages are enabled, then the data is continuously placed in the port buffers. The data is continuously placed in the port buffers in order to allow transmission of the data at the established baud rates.
The data will appear as a continuous string of numbers that represent hexadecimal values of ASCII characters.
The first 4 bytes of every IID that are “broadcast” or that are one time “read/write”, consist of a “Standard Preamble”. The first byte of the M5X message or the M50 message is always the character “$50”. The “$50” character indicates the beginning of the message. The second byte represents the module that is sending the message. The interface device should use the character $00 in the second byte. All of the responses from the PL1000T will use the character $01 in the second byte. The basic format for the M5X message protocol or the M50 message protocol is shown in Illustration 8.
|$11||Activate Broadcast List||X||X|
|$12||Deactivate Broadcast List||X||X|
|$13||Program Broadcast List||X||X|
|$15||Status Response to IID $11, $12, $13||X||X|
|$1A||Advanced Broadcast Response Data||X||X|
|$1C||Advanced Broadcast Activate||X||X|
|$1D||Advanced Broadcast Deactivate||X||X|
|$1E||Advanced Broadcast Setup||X||NA|
|$1F||Status Response to IID $1C, $1D, or $1E||X||NA|
|$24||Single Parameter Read Request||X||X|
|$25||Single Parameter Read Response||X||X|
|$34||Single Parameter Write Request||X||X|
|$35||Single Parameter Write Response||X||X|
|$80||Composite Data Response||X||NA|
|$81||Program Composite Request||X||NA|
|$82||Diagnostic Data Request||X||X|
|$85||Response to Request IID $81||X||NA|
The electronic controller of each engine can be configured to use different “Module Identifiers” (MID). The module identifier has also been referred to in previous documents as a “Unit Number”. The M5X protocol or the M50 protocol uses the MID in order to identify each engine controller that is on the network. Most of the engine controllers are configured at the factory with the default address of $24. The $24 character represents the hexadecimal number 24. If there is a need to identify, confirm, or change the MID of an electronic engine controller, refer to the System Operation Test and Adjust manual for the specific engine.
If either of the following situations occur in the network, then the MID for the engine controllers may be reviewed or modified.
- More than one electronic engine controller is connected to the CDL network in the system to the same serial port on the PL1000T.
- More than one Caterpillar EMCP or other generator set control panel device is connected to the CDL network in the system to the same serial port of the PL1000T.
Refer to Table 3 for a list of typical MID error codes for engine controllers. For information about the MID for a specific engine application, refer to the appropriate publication that was distributed with the engine model.
Error Codes for Engine Controllers
|33||Engine Control #2|
|34||Engine Control #3|
|35||Engine Control #4|
|36||Engine Control #1|
|37||Engine Control #5|
|38||Engine Control #6|
|40||Engine Control #7|
|41||Engine Control #8|
|47||Backup Engine Control|
The checksum is an important part of the M5X protocol message and of the M50 protocol message. The checksum is calculated the same way for both protocols. This document includes necessary considerations related to checksum calculation.
The checksum provides a mechanism by which the integrity of each message and associated data is maintained. When a message is received, the checksum is calculated and the message integrity is validated in order to confirm that the received data is the intended information. Each message sent contains a checksum located in the next to last byte before the ASCII carriage return character string “$0D”. Checksum values are calculated by determining the twos complement value of the hexadecimal summation of all data bytes in the message. The message is valid if the summation of all data bytes is zero. Refer to Table 4 for an example.
For example, consider the following message string:
|Byte||ASCII Value||Hexadecimal Value|
Truncated to LSB
Truncated to LSB
Remember that the message is transmitted as ASCII characters, but the message checksum is based upon the hexadecimal values of each byte of data string message. In the example, $AE is the checksum. Since the 2’s compliment of the hexadecimal summation equals zero, therefore, the message is known to be valid.
The heartbeat message is a method used to continuously monitor and verify the PL1000T data stream. The heartbeat message should be used in order to verify the PL1000T connection before the login process. The heartbeat message should be used periodically during normal operations. The heartbeat PID is $F0 $12 that uses a “Single Parameter Read IID” $24.
Periodic read requests and received responses will serve to validate the RS-232 connection. Periodic read requests and received responses will provide the capability to monitor the security level of the PL1000T for unexpected changes. Unexpected changes in the security level received in the heartbeat response message may prevent some data from being transmitted.
Every individual PID that is supported by the engine electronic controller has an associated security level 0, 1, 2, or 3. Likewise, there is a security level associated with every PID that is supported by the PL1000T. The security levels are numerically related in an “equal or lower” relationship. For instance, when the security level response indicates a security level of 2, any PID with a security level of 3 would not be accessible. For troubleshooting information and procedures related to security level issues, refer to the Systems Operation Test and Adjust manual.
Table 5 lists the PIDs that are supported by the PL1000T and also lists the associated security level requirements.
|Associated Security Levels of PL1000T Supported PIDs|
The first step toward establishing protocol communications with the PL1000T is to perform the login procedure. Login must be accomplished before any PIDs can be assessed. The login procedure consists of sending the appropriate password to the PL1000T via IID $34 writing to PID $AA $8A. All PL1000T communication modules are shipped from the factory with blank passwords. To log in to a PL1000T with a blank password, send the following message.
Note: This message assumes the PL1000T is configured as module number 1. If the PL1000T is not configured as module number 1 for the specific application, then the appropriate checksum will need to be formatted. Also, the appropriate checksum will need to be calculated for the specific application.
Additionally, a separate and unique password can be programmed in for each of the security levels 1, 2, and 3. At login the PL1000T security level is transitioned to the level associated with the password used to log in. Using the method security levels can be customized for different users or devices that access the PL1000T. The password example above assumes the factory default of a “blank” password, and the security level is set to the highest level of 3.
If the password for security level 1 is set to “11112222”, then the login would consist of the items shown in Illustration 10.