MDS 05-4846A01, Rev. F
SD Series Technical Manual
25
COM2 PORT NOTES & WIRING ARRANGEMENTS:
• RXD+ / RXA and RXD– / RXB are data sent
into
the radio to be transmitted out
• RXD+ / RXA is positive with respect to RXD– / RXB when the line input is a “0”
• TXD+ / TXA and TXD– / TXB are data
received
by the radio and sent out
• TXD+ / TXA is positive with respect to the TXD– / TXB when the line output is a “0”
Invisible place holder
Figure 20
.
RS-422/485 Wiring Arrangements
8
OUT
CTS (Clear-to-Send)—
Goes “high” after the programmed
CTS delay time has elapsed (DCE), or keys another
connected radio when RF data arrives (CTS KEY).
9
--
Reserved—User I/O for special applications
Table 9. COM2 Pin Descriptions
—Radio in RS-422/485 Mode
Pin
Number
Radio
Input/
Output Pin Description
1
OUT
Carrier Detect/Link
—A low indicates signal received.
2
OUT
TXD+/TXA
(Received Data +)—Non-inverting driver output.
Supplies received payload data to the connected device.
3
IN
RXD+/RXA
(Transmitted Data +)— (Transmitted Data +).
Non-inverting receiver input. Accepts payload data from the
connected device.
4
IN
Sleep Mode Input
—Grounding this pin places the radio in a
low power consumption mode.
5
--
Ground
—Connects to ground (negative supply potential) on
the radio’s PC board.
6
OUT
Alarm Output
—
Behavior is user-configurable.
Default
behavior:
A high on this pin indicates an alarm condition; a low
indicates normal operation.
7
IN
RXD-/RXB
(Transmitted Data -)— Inverting receiver input
8
OUT
TXD-/TXB
(Received Data -)
—
Inverting driver output.
9
--
Reserved—User I/O for special applications
Table 8. COM2 Pin Descriptions
—Radio in RS-232
Pin
Number
Radio
Input/
Output
Pin Description
EIA-485 2-WIRE CONNECTIONS
TXD +
RXD +
2
3
7
RADIO
DA
T
A CONNECT
OR
8
RXD –
TXD –
EIA-422 4-WIRE CONNECTIONS
RXD+/TXD+
2
3
7
RADIO
DA
T
A CONNECT
OR
8
RXD–/TXD–
EXTERNAL
DEVICE
EXTERNAL
DEVICE
RXD –
TXD +
RXD +
TXD –
RXD –
TXD +
RXD +
TXD –
This jumpering must be provided by user.