Allen-Bradley 1747-OC Series, User Manual

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1747-UM001A-US-P - March 2000
7-2 Using the Open Controller
Using the Serial Ports Both open controller CPU modules have two serial ports that are electrically
isolated from the backplane but share a common isolated ground (Figure
7.2).
COM1 and COM2 are configurable through the DOS
mode
command
(
mode com
n b
) for 110, 150, 300, 600, 1200, 2400, 4800, 9600, 19200 bit/
sec. For example, at the DOS prompt, enter:
MODE COM2 48
to specify
4800 baud rate.
Figure 7.2
Connecting to the serial ports
In RS-422, the TXD lines are enabled when RTS is enabled. When RTS is
disabled, the TXD lines go to tristate (offline).
COM1 supports RS-232 only.
COM2 supports RS-232, RS-422, and RS-485. You set a jumper on the
open controller CPU to select the COM2 mode of operation (Figure 7.3).
The jumper location and settings are the same for both open controllers.
STATUS BATT
COM 1
LED 1 LED 2
LED 3 LED 4
COM 2
OC 586 CPU
STATUS
BATT
COM 1
LED 1 LED 2
LED 3 LED 4
COM 2
OC 266 PENTIUM CPU
2 serial ports
Use 9-pin, D-shell adapter
cable 1747-OCS92
See table for maximum
cable lengths
Maximum lengths for serial cables
For: Maximum cable length is:
RS-232 50 ft (15.24 m)
RS-422 4000 ft (1219.20 m)
RS-485 4000 ft (1219.20 m)
Pin assignments
Pin RS-232
RS-422
(COM2 only)
RS-485
(COM2 only)
1 DCD 422 TXD+ TRXD
2 RXD 422 RXD+
3 TXD
4 DTR
5 common common common
6 DSR 422 RXD–
7 RTS
8 CTS 422 TXD– TRXD
9 N/C N/C N/C
1747-OCE
1747-OCF