Red Lion GCM422 - Manual (Page 4)

TYPICAL RS-422 CONNECTIONS
NOTES:
1. Connect shield drain wire to earth ground.
2. RS-422 polarity: Terminal “A” is negative with respect to terminal “B”
in the mark (logic 1) condition.
3. If the RS-422 receive data inputs are not connected, the 20 mA SO output
will be indeterminate. Therefore if the receive data input is not
connected, the 20 mA SI input loop on the Red Lion Controls product
must be wired for the mark condition (current flowing) and must be
disconnected from the SO output terminals on the GCM422 Module.
4. Current flowing is a stop bit (mark) and no current flowing is a start bit
(space).
FIGURE 4
TYPICAL RS-485 CONNECTIONS
Note: Connect shield drain wire to earth ground.
For RS-485 operation, place the internal jumper in the 485 position. The
transmit and receive data lines of the GCM422 module should be wired
together. The transmit disable input must be high (+ 5 VDC) in order to
transmit data from the module (Note: This input is internally pulled high).
To receive data from an RS-485 device, the transmit disable input must be
low which forces the transmit data output into a high impedance state,
effectively disconnecting it from the two-wire bus.
Current flowing is a stop bit (mark) and no current flowing is a start bit
(space).
FIGURE 5
TYPICAL RS-485 TO LEGEND CONNECTION
FIGURE 6
TROUBLESHOOTING
For further technical assistance, contact technical support at the appropriate company numbers listed.
Red Lion Controls
20 Willow Springs Circle
York PA 17402
Tel +1 (717) 767-6511
Fax +1 (717) 764-0839
Red Lion Controls AP
31, Kaki Bukit Road 3,
#06-04/05 TechLink
Singapore 417818
Tel +65 6744-6613
Fax +65 6743-3360
Red Lion Controls BV
Basicweg 11b
NL - 3821 BR Amersfoort
Tel +31 (0) 334 723 225
Fax +31 (0) 334 893 793