Hello.
I want to communicate between two M91 plc-s (M91-2-T38) with RS485, MODBUS protocol.
When i connect the PLC-s with the cable the communication works well.
My problem is, that the distance between both PLC-s is to long, so i must use optical fibers.
I have two RS485<->optic converters. But the communication dont work.
So if you have some ideas what can be wrong or what i must to observe with that kind of connection, please let me know.
Is there any other possibility to communicate between those two PLC-s (some signals (MB, MI)).
Thank you.
