CAN J1939 - Adjust engine RPM

FenrisUlven70

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F
Join Date
Jan 2017
Location
Stavanger
Posts
2
Hi

I have a AB Compact logix connected with a HMI x-way Ethernet/IP to CAN J1939 Converter that is connected to a CAT engine.
I have an Input and output offset on 4 bytes in the x-way due to internal use in the module.
I am able to read the motor data that I want, but I am not able to adjust the engine throttle (write data).
I have tried SPN91 in PGN61443 (byte 2) resolution 0.4%/bit and SPN515 in PGN65247 (byte 2 and 3) resolution 0.125 rpm/bit in byte 2 and 32rpm/bit in byte 3 but with no success.
Is there any enable / disable bits that needs to be activated? I'm stuck. Any tips?
 
FenrisUlven70 said:
Hi

I have a AB Compact logix connected with a HMI x-way Ethernet/IP to CAN J1939 Converter that is connected to a CAT engine.
I have an Input and output offset on 4 bytes in the x-way due to internal use in the module.
I am able to read the motor data that I want, but I am not able to adjust the engine throttle (write data).
I have tried SPN91 in PGN61443 (byte 2) resolution 0.4%/bit and SPN515 in PGN65247 (byte 2 and 3) resolution 0.125 rpm/bit in byte 2 and 32rpm/bit in byte 3 but with no success.
Is there any enable / disable bits that needs to be activated? I'm stuck. Any tips?
Click to expand...

I have no experience with CAT. But other equipment, on CAN, or Devicenet, or Profibus, or whatever ... needs to be configured to take the setpoints from the network. So you may need to set the CAT engine to take speed reference from CAN as well as whatever is telling it to run at the speed it is now running.

Both methods that you describe should work, if they are enabled. Since you have at least 2 methods, I would expect that you need to tell the CAT engine controller how to figure out which setpoint to use.
 
If the CAN protocol is anything like PLC's you can only have one master. I'm assuming that when you say you're connected to the CAT engine that you are talking to the ECU monitoring/controlling the engine. In a PLC if I want to control an output (via software) that is being controlled by the PLC's ladder code I have to "force" the output. I would guess that you would have to do the same thing with the ECU.
 
FenrisUlven70 said:
Hi

I have a AB Compact logix connected with a HMI x-way Ethernet/IP to CAN J1939 Converter that is connected to a CAT engine.
I have an Input and output offset on 4 bytes in the x-way due to internal use in the module.
I am able to read the motor data that I want, but I am not able to adjust the engine throttle (write data).
I have tried SPN91 in PGN61443 (byte 2) resolution 0.4%/bit and SPN515 in PGN65247 (byte 2 and 3) resolution 0.125 rpm/bit in byte 2 and 32rpm/bit in byte 3 but with no success.
Is there any enable / disable bits that needs to be activated? I'm stuck. Any tips?
Click to expand...
Hi we have been using these for several years, mainly to read data but can definitely write to ecu .
ill have a look for example but if you peruse the x-gateway manuals thoroughly it will explain it.
its a bit of a cow to read but it is correct
 
Hi Thingstodo

Tank you for the feedback. We had a technician from CAT here that changed primary throttle from PWM to CAN, but it did not help. In this network there is the CAT ECU (Node, I do not know) a CAT panel and my x-way bridge. I'm reading data from the CAT using broadcast. I'm also using broadcast when I try to write to the PGN's mentioned in the origin post.
 
Try pretending to be a different module on the network. I've found before (and I think that it was with a CAT engine) that I had to pretend to be a transmission or something similar for the CAT engine to listen to my RPM commands. Apparently not everybody is allowed to tell the engine what to do.

Source Address
The last 8 bits of the 29-Bit message identifier contain the source address, i.e. the address of the transmitting ECU (node). There is a total of 253 addresses available and every address must be unique within the network, i.e. ECUs cannot share addresses. PGNs, however, are independent of the source address, meaning every ECU is allowed to transmit any message.
Click to expand...

http://www.simmasoftware.com/j1939-sa.html
 

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