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An MS/TP network can consist of multiple network segments.

Each segment of an MS/TP network must:

• Be wired in a daisy-chain configuration

• Be no longer than 2000 feet (610 meters)

• Have 32 or fewer devices (controllers and repeaters)

• Have one of the following:

○ The End of Net switch set to Yes on the Open controller that is at the end of the network segment. This adds bias and prevent signal distortions

MS/TP communications wiring

Avoiding noise

Avoid running communication wires or sensor input wires next to AC power wires or the controller's relay output wires. These can be sources of noise that can affect signal quality.

igniters Large contactors
transmitters Fluorescent lights
Variable speed drives Parallel runs with power lines
Transformers Video display devices

*If noise is a problem and you cannot move the wiring, use ferrite clamp-on chokes on the cabling to improve signal quality


Troubleshooting an MS/TP network

If you can not discover a controller or have no communication to a device or devices on an MS/TP network:

Verify that the entire segment uses the same baud rate

Verify device check address.

Verify the following aspects of wiring

The shields on all controllers are connected properly. The shield must not touch the metal housing or tie to earth ground.

The cable's outer jacket is not stripped more than one inch. If so, the wires may have become untwisted, causing signal reflections.

The wires are connected correctly to the terminal blocks.

White wire to Net+ (typically, terminal 1 on a controller)

Black wire to Net- (typically, terminal 2 on a controller)

Shield wire to Shield (typically, terminal 3 on a controller)

Verify that your network meets the MS/TP network requirements and the Network segment requirements.No more the 32 devices without a repeater and end of line resisters at both ends.