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Problem wih V120 and EX-RC1 - CanBus communication

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Hello, I have problem with Can Bus communication between V1210 and EX-RC1

The system is working from 6years in one moment the EX-RC1 - Buss comm indicator starts blinking in green.
We make following:

- Change the module EX-RC1 with new one
- Cheack wiring and termination resistor - it's OK
- Traying different cable - the same issue
- Update bothe PLC and EX-RC1 - firmware, boot, os and etc.
- Check communication with software on Connection module / Network of Visi Logic 

- V1210 - is green after test ot address 1 
- EX-RC1 - is green after test ot address 2

Addres 2 on EX-RC1 is hardware adjusted by jumpers

The strange is that this is working system without changes from years.....
Please help....

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  • MVP 2023

Since you replaced the EX-RC1 module, checked the conductors (by replacing), the power supply of the CAN modules, remains the only culprit - the PLC itself.

I do not recommend anyone to repair the PLC - but you are probably convinced that the CAN transmitter in PLC  is probably faulty.

You can hire an electronics specialist to test the internal CAN module on the PLC's internal board. There is a well-known chip 78M05 - linear power converter + 5V and  CAN driver 82c250 on the PLC motherboard reverse side. Due to the fact that the system worked for a long time without any problems, I think that the 78M05 chip failed.

P.S. However, I recommend - once again check the correctness of the power connection (not reverse polarity) and the correct connection of the СAN bus wires. Sometimes the system stops working after someone else's intervention, which is unknown. And we have to look for a problem in places where there are no mistakes.

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  • MVP 2023

Further to all that Kratmel has said, which is likely correct, ensure that everything connected to the RC1 is OK.  Test what happens if you disconnect all modules and all power perhaps shared at that end and see what happens.

Kratmel's statement

13 hours ago, kratmel said:

Sometimes the system stops working after someone else's intervention,

is so true!  One can often get to a site and find an alteration, new high voltage gizmo fitted nearby, unclamped extra solenoids etc fitted.  The list is endless!



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You may check for short circuit between 0V and H, 0V and L, H and L on CANBUS connector.

Resistance should be tens of kilobytes.

*Disconnect cable before you make measyrement.

For example, resistance between H and L is near 36 kB for V570, V1xxx.

Low resistance or shortcut point to hardware problem.


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  • 1 year later...



I'm a novice at this and have just got a v1210 touch screen and want to remote i/o's with CANbus. but if I'm honest haven't a clue how to do this. what ladder program have you used to make the CANbus communicate between the V1210 and the EX-RC1?

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Here is where to look for information :

Programming Examples :

Help -  Examples - V900 - Project Examples -  Communications - EX-RC1     >  Examples there to work with.

EX-RC1  uses the RS232  Programming port to set the program inside   Note :   57k Baud Rate MAX !!

Just a note:     Analog Data is sent  as integers and received as integers

                              Inputs and Outputs( Bits)  are encoded  to    Bytes ( 8 Bits  = 1 Byte)    asent and then decoded  at  the other end.

                                So pay attemtion as to where the data ends up. Once Understood, it works.


Canbus Wiring :

Review         Help   - CANBUS -- Getting Started with CANBUS   - Specs and Wiring.

Use   Proper CANBUS/Devicenet Cables. 

CANBus  cabling is NOT Powered by  the PLC, so POwer must be applied to the CANBUS  Power Wire  Pair

Review the Addessing  for the Module and the PLC


If you have issues, you can Post Your Code for assistance. 





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