Canbus Assistance

Hello everyone, I am involved in an application using an Isuzu engine driving an off highway vehicle. The engine is fully Canbus.

I am using a touchscreen for user interface, and a Modbus capable plc for control.

For the Canbus to Modbus interface I am using a BridgeWay AB7606, J1939 to Modbus.

My problem is that I am a Canbus newby, I have to map my Modbus memory locations to be able to receive the canbus messages, most of the messages from the engine bus will be broadcast, but I will also be selecting set engine RPMs by sending messages to the bus.

I have a list from Isuzu with the can codes but I am stumped from there.

Can anyone point me in the right direction of a website with some really good canbus info.

Thanks,

EdmontonControls said:

Hello everyone, I am involved in an application using an Isuzu engine driving an off highway vehicle. The engine is fully Canbus.

I am using a touchscreen for user interface, and a Modbus capable plc for control.

For the Canbus to Modbus interface I am using a BridgeWay AB7606, J1939 to Modbus.

My problem is that I am a Canbus newby, I have to map my Modbus memory locations to be able to receive the canbus messages, most of the messages from the engine bus will be broadcast, but I will also be selecting set engine RPMs by sending messages to the bus.

I have a list from Isuzu with the can codes but I am stumped from there.

Can anyone point me in the right direction of a website with some really good canbus info.

Thanks,

Click to expand...

You could start here: http://www.canbus.us/
and here: http://www.can-cia.org/

Thanks Norm, I checked out the sites. I will know doubt have a few questions later.

EdCo

I checked out the Canbus info on the internet and I am a bit lost, if someone could get me started, I have the following from the ISUZU documentation:

Canbus

Engine oil pressure
SPN = 100
transmission repetition 500 msec

Arbritration field
P = 6
R = 0
DP = 0
PF = 254
PS OR GE = 239
SOURCE ADD = 0

Data Field
DL = 8
BYTE = 4
BIT = 8-1
DATA RANGE = 0-1000kpa
RESOLUTION = 4kpa
OFFSET = 0
DEFAULT DATA = 0

The configuration software for the BridgeWay AB7606 has the in the J1939 Input and Output I/O Tables

Table Offset (I presume this would be 0)
Data Length ?
PGN ?
Target Address (I presume this would be the Modbus Address)
Update Rate 500ms
Message offset ?

More information; I want to receive as much info from the engine as I can, such as Engine RPM, Coolant Temp, Oil Pressure, Inlet Temp,Filter Warnings, etc.

I only have to transmitt one message to the engine and that is to request a set engine speed.

I don't know if this helps, but I am looking for any guidance I can get as I am a complete newby when it comes to CanBus.

EdCon

I have been working regularly with Caterpillar sets for some time now that have J1939 through a Modbus RTU converter to my PLC. The re-mapping is already done in the module but I then have to do a pile of calculations - place evrything into floating point values - take the value, divide by the divisor, subtract the offset and away you go. J1939 is a bit of a pain that way - Modbus would be so much easier..

For starters, saying canbus doesn't really tell us anything except the wiring and bit timings.

There are many standard protocols based on canbus and a myriad of user specific ways to use it. Some standard protocols based on canbus are:

• CanOpen
• DeviceNet
• J1939

What you really need to find out what standard, if any, Isuzu is using and then get the definition of that standard or protocol.

Our friend had already stated it was J1939 - this is the protocol that has been adoptred by Caterpillar, MTU, Deutze, apparently Isuzu, and even Cummins have a J1939 prototype I am working with at the moment. There are almost certainly others.

Some of the Woodward generator controllers talk J1939 as well - along with the Woodward LS4 circuit breaker controllers. The Woodward GCP31 also has additional components available to talk to diesel engines directly and can be used to start and stop engines over the bus, collect engine data, perform shut downs etc etc.

Caterpillar have 2 J1939 busses - an internal one for their own use and an external one for external devices.

When I get time - probably 2 centuries away - I plan to use an Omron CAN Open PLC card and set up direct J1939 communications to engines without having to fiddle about with Modbus RTU.

I was just trying to be careful. He said he had a Modbus to J1939 converter but that doesn't mean that is what he really needs. I don't know enough about J1939 to know if the data he posted fits with it or not. I'm more of a CanOpen type.

Sorry if I caused anyone any confusion.

Thanks for the info so far folks, does anyone have any comment on the data I have posted from the Izuzu manual?

EdCon

You will not have a Modbus address - only a CanBus address.

I cannot help you with Canas I have not been there YET.