Technical data

A-B SuperBridge Technical Reference
10
SETTING UP COMMUNICATIONS WITH THE MCS
The MC network is a four wire RS-485 Master-Slave polled communications loop. All MCs are
slaves on the network, and are required to have a RS-485 serial port and a unique address,
called “Controller Number” (CN). The CN is set up, along with other serial communications
parameters, in each MC. SB is the master, and must have either a four wire RS-485 or a RS-422
serial port.
MC Physical Connection
Use a RS-422 type two pair shielded cable like Belden 9368. One pair is used to carry signals
from the SB transmitter to all MC receivers. The other pair is used to carry signals from all MC
transmitters to the SB receiver. The following table lists connections, using an A-B 1771 DXS2
Information Processor port, strapped for RS-422 communications. Other RS-422 adapters may
have other pinouts.
SB
Signal
SB 1771
DXS2 Pin #
(DE-9 P)
ULTRA
-485 Pin #
(DB-25P)
FASTCOM
422/4 Pin #
(DE-9 S)
MC³
Controller
Terminal #
MC² Controller
Pin #
(DB-25S)
MC
Signal
Tx+ 1 24 4 3 22 Rx+
Tx- 9 25 5 4 23 Rx-
Rx+ 2 12 8 1 24 Tx+
Rx- 6 13 9 2 25 Tx-
Shield 5 7 1 N.C. 11 Shield
Be careful when running the cable. Avoid power lines and other devices that might cause
electrical disturbances. Maximum cable length is 1230 m (4000 ft). See also [1], pages 3-2 and
D-1. SB does not have to be connected at one end of the cable. Remove all termination resistors
in the MC² serial ports. Add a 150Ω terminating resistor between the + and - lines for each pair at
each end of the cable.
If only one MC² is used, it is possible to use a RS-232 interface instead. This is useful for bench-
testing SB, using a regular office PC, which normally has no RS-422 interface. The cable should
have a DE-9S, for a 9 pin connector in the PC or a DB-25S, for a 25 pin connector in the PC in
the PC end and a DB25P in the MC end. Use the following table for the pinout, and keep the
cable length less than 25 feet at 19200 baud.
Signal, PC side. PC COM port,
9 pin (DE-9P)
PC COM port,
25 pin (DB-25P)
MC² Serial port
(DB-25S)
Rxd (PC Receiver) 2 3 15
Txd (PC Transmitter) 3 2 12
Ground 5 7 7
Shield 1 1 1
MC Communication Parameters
MC Communication parameters are set in the controllers themselves. They are:
1. Controller Number. Must be different for each controller. Start with 1 and continue up.
2. Baud Rate. Must be the same for all controllers. Set to the highest possible, normally 19200.
Some older software versions only support up to 9600 baud. See Model Specific Information
(page 23).