Users Manual

MDS 05-6399A01, Rev. G MDS™ Master Station 105
Table
6
-
7
.
COM2 Pin Descriptions
—
Radio in RS
-
232 Mode
Pin
Number
Radio
Input/
Output
Pin Description
Table
6
-
8
.
COM2 Pin Descriptions
—
Radio in
RS
-
485 Mode
Pin
Number
Radio
Input/
Output
Pin Description
1 --
Reserved—Do not connect
2 --
Reserved—Do not connect
3 --
Reserved—Do not connect
4 -
Ground—Connects to ground (negative supply potential) on
the radio’s PC board.
5 IN
TXD+/TXB (Transmitted Data +)— Non-inverting receiver
input
6 OUT
RXD+/RXB
(Received Data +)
—
Non-inverting driver output.
7 IN
TXD-/TXA (Transmitted Data -)— Inverting receiver input
8 OUT
RXD-/RXA (Received Data -)— Inverting driver output.
COM2 RS-485 and RS-422 Wiring Arrangement
- RXD+ / RXB and RXD– / RXA are data received by the radio and transmitted
- RXD+ / RXB is positive with respect to RXD– / RXA when the line input is a “0”
- TXD+ / TXB and TXD– / TXA are data sent to the radio to be transmitted
- TXD+ / TXB is positive with respect to the TXD– / TXA when the line output is a “0”
Table 6-9. EIA-422 4-Wire Connections
External DB-9 COM2
TXD- 2 7 TXD-
RXD- 3 8 RXD-
RXD+ 7 6 RXD+
TXD+ 8 5 TRD+
Table 6-10. EIA-485 2-Wire Connections
External DB-9 COM2
TXD- 2
RXD-/TXD-
RXD- 3
RXD+ 7
RXD+/TXD+
TXD+ 8