Goals and Symptoms

What is the pinout for connecting to a 984 CPU using Modbus?

Facts and Changes

9 pin to 9 pin

Causes and Fixes

The Modbus (DB9 to DB9) pinout is as follows:
Pins 2 and 3 will cross,
Pin 5 Straight through,
Pins 4 and 6 will cross,
Pins 7 and 8 jumper back to each other on both sides.