Experimental Physics and
Industrial Control System

Hi Ralph,

I have been running Modbus/TCP from a 64-bit Linux OS under EPICS R3.14.11
using ASYN 4-16 and Modbus 2-1 and have not noticed any issues like this.

I'm using Modbus functions 1 & 4 with single 16-bit word access and read
only. Would these messages show up on the IOC console?
I'm not specifically looking at the CRC which is why I asked where I
would see the messages at or how I would be able to see them would probably
be a better question. I'm not certain that my device supports CRC either.

Marty

Ralph Lange wrote:

Hi,

I am reliably getting CRC errors on the device's answer when reading
more than two parameters (Modbus code 3) through serial RTU on RS-485
from a Wave P6100 temperature controller. The data itself looks good and
reasonable.
One or two word access (Modbus code 1 or 3) seems to work fine.
The IOC runs on 64bit Linux, using Mark Rivers' Modbus on ASYN driver.
(All from synApps 5.5)

Has anyone seen similar behaviour?
Does anyone successfully run Modbus/asyn on 64bit Linux? (To rule out 64
bit issues in the CRC checking part.)

Thanks for any help,
~Ralph

References:

CRC issues using Modbus/asyn on 64bit Linux Ralph Lange

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