Reading Modbus TCP/IP thru Cisco 2960 getting Timeout Errors
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09-19-2022 10:47 AM
Hi all,
I'm having some odd issues when trying to read Modbus TCP registries from a Modbus device to a Schneider PLC via a Cisco 2960X. From what I've read, there no need to set much configuration on the Cisco 2960X. Since the PLC will act as the Modbus TCP Server.
Modbus TCP device <---> Cisco 2960x <---> Schneider PLC
The read command occasionally times out and gives back a read timeout error. So we are getting data once in a while. Once thing we have noticed is that the Modbus device is only 10BaseT, though the 2960x is noted to be compatible with 10/100/1000.
Let me know if you've come across anything similar, thanks!
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09-19-2022 10:30 PM
- Check port counters for the ports where the modbus and Scneider is connected to.
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '
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09-20-2022 07:18 AM
Hi M,
Thanks for the pointer. We checked the port counters and are getting a few input errors at the port, everything else is 0. The number of input errors are not consistent with the time-out errors, but does probably point to over utilizing the port? Even though I'm only reading 100 registers (200 bytes) every 2 seconds. I would not think that would get input errors.
I tried doing a continuous ping to the device and not get any lost packets, but still have time-out errors.
Would enabling QoS help?
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09-20-2022 11:10 PM
- Note sometimes, some of these devices (types) can not do full duplex, check documentation and or configure port settings to half duplex , if needed.
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '
