Hi,
I am using cRIO and 9871 (RS485 module) for communicating with a device using MODBUS protocol. I have converted the Full Duplex interface of 9871 into a Half Duplex interface using a small custom proto cable (see attached schematic). Also I want to check the communication with the device over a distance of 1000 feet. As I do not have 1000 feet of cable so I am using a resistior to simulate the 1000 feet lenght for the following cable specs
AWG - 22, Cable resistance / 1000 feet = 16 Ohms
When I remove this resistor from the line I am able to talk with the device successfully, but when I insert this simulator in the line even though I get a 2V peak-peak differential signal at the input of 9871 I am unable to establish communication between 9871 & my device.
Please let me know what could be a possible solution to this problem.
Vikas
