RJ-Style Modular Jack and Cables for SA Bus - Metasys - LIT-12011034 - General System Information - Metasys System - Release 11.0

MS/TP Communications Bus Technical Bulletin

Product name
Metasys System
Document type
Technical Bulletin
Document number
Release 11.0
Revision date

The 6-pin modular jack SA bus connection (Figure 1) is a straight-through (not a crossover) connection and that uses a 6-wire connector cable (with 6-pin RJ-style modular jacks) to connect SA devices to network sensors , DIS1710 Local Controller Display, and the VMA Balancing Sensor. On the 6-wire cable, two wires are used for network communication, two wires for network sensor power, and two wires supply 15 VDC (200 mA maximum) power to the devices connected to the sensor.

The cable connected to the SA bus 6-pin modular jack is a straight-through cable and cannot exceed 30 m (100 ft). Do not use crossover cables on the SA bus.

The SA bus 6-pin modular jack supports only one device and no other SA device may be daisy-chained to the port.

Important: Failure to adhere to these wiring details may cause your network sensor to function incorrectly. You are not able to connect to the system using the Handheld Variable-Air-Volume (VAV) Balancing Sensor, nor can you expand the system with future offerings.

Every MS/TP device (except the NAE55) has at least one 6-pin modular jack. Modular jacks on the network sensors allow you to connect a VMA Balancing Sensor.

Note: Do not mix RJ-style modular (phone) jack and screw terminal devices on the SA bus. Due to the permanent internal SA bus EOL termination contained in CGMs, CVMs, FACs, FECs, VMAs, XPMs, and IOMs , using both the phone jack and terminal block effectively puts the EOL termination in the middle of the SA trunk, creating a star network configuration. This configuration violates the RS-485 network wiring guidelines and can cause unpredictable communication problems.
Figure 1. 6-Pin Modular Jack Pinout Details