Gill Instruments Ltd
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MaxiMet
Page 21
Issue 3
Doc. No. 1957-PS-021
May 2018
Suggested maximum cable lengths for supported communication networks
Communication format
Baud rate
Max. cable length
RS232
19200
6.5m
RS422/RS485
19200
1000m
SDI-12
1200
90M
GMX531/541/550/551
Max. cable length
Contact switch closure
Switch resistance plus there and back cable resistance to
be less than 20 ohms.
4.4.
Connections
Any cable wires not used should be isolated and grounded at the terminating equipment/user end. Digital
0V should be used in conjunction with RS422 Tx/Rx lines in order to improve noise immunity.
4.4.1 View of the MaxiMet Connector looking down at the Cable Side
4.4.2 9-Way Connector and Cable Connections
9-Way Connector
Number
Signal Designation
1
Signal Ground
2
ve
3
Supply –ve
4
RS422/485 TXD+
5
RS232 TXD, RS422/RS485 TXD-
6
RS422/RS485 RXD+
7
RS232 RXD, RS422/RS485 RXD-
8
Comms Select Only.
Applicable if MaxiMet COMMS Interface Setting set for EXT using
MetSet. If MaxiMet is set for EXT Comms then:-
For RS232 connect Pin 8 to Pin 2 +ve.
For RS422 leave Pin 8 open circuit or connect to Pin 3 –ve.
9
SDI-12 Data