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+--- Thread: Modbus Error Log (/showthread.php?tid=3305)
Modbus Error Log - khalil - 18.04.2021
Hello
I have errors in the Modbus error Logs but the slave devices are working, I can read and write.
errors are:
- read failed: operation timed out
- read failed: response not from requested slave
I got a lot of these errors in the error log
is it ok to see these errors?
Note that I have slave devices on Modbus TCP with no errors
RE: Modbus Error Log - admin - 19.04.2021
It means that there are some minor issues with the RS485 communication.
Some things to consider:
1. Connect GND between all Modbus devices (read this: https://store.chipkin.com/articles/rs485-rs485-cables-why-you-need-3-wires-for-2-two-wire-rs485)
2. Install 120 ohm terminator resistor on both ends of the RS485 bus
3. Topology: daisy-chain connection is recommended. Short stubs are OK as well, never use star topology
4. Try using a lower baud rate if devices allow this
RE: Modbus Error Log - khalil - 19.04.2021
(19.04.2021, 06:25)admin Wrote: It means that there are some minor issues with the RS485 communication.
Some things to consider:
1. Connect GND between all Modbus devices (read this: https://store.chipkin.com/articles/rs485-rs485-cables-why-you-need-3-wires-for-2-two-wire-rs485)
2. Install 120 ohm terminator resistor on both ends of the RS485 bus
3. Topology: daisy-chain connection is recommended. Short stubs are OK as well, never use star topology
4. Try using a lower baud rate if devices allow this
Thank You, Admin