Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 44)

Chapter
Using the Communication Ports 2
2 -6
You can operate PRT1 and PRT2 ports full-duplex and DH485 port
half-duplex at 300, 600, 1200, 2400, 4800, 9600 or 19200 bit/s. You can
set the communication rates for PRT1, PRT2, and DH485 ports using the
MODE (page 11 -20) statement and store the settings using the PROG1
(page 10 -12) and PROG2 (page 10 -13) commands. You can set the
communication rate for the program port with CALL 78 (page 13 -8).
Important: Jumper JW6 sets the communication rate on the hardware for
PRT2 (page 1 -8). You can also select the communication rate for PRT2
within your program. The settings you select before using PROG1 or
PROG2 override the jumper setting until the module is powered down.
The settings you select with MODE overrides both the jumper and the
PROG1 and PROG2 settings until the module is powered down. If you
use the PROG1, PROG2 or MODE to store the port settings in the user
EEPROM, the unit then powers up with stored configuration.
Important: The BASIC module cannot transmit and receive continuous
streams of data at 19.2k bit/s on all three ports at the same time.
Here is the communication rates vs distance:
Communication Maximum distance allowed in meters (feet) for:
Rate (bit/s) RS-232 RS-423 RS-422 RS-485
300 15 (50) 15 (50) 1230 (4000) 1230 (4000)
600 15 (50) 15 (50) 1230 (4000) 1230 (4000)
1200 15 (50) 15 (50) 1230 (4000) 1230 (4000)
4800 15 (50) 15 (50) 1230 (4000) 1230 (4000)
9600 15 (50) 15 (50) 1230 (4000) 1230 (4000)
19200 15 (50) 15 (50) 1230 (4000) 1230 (4000)
Important: Use the RS-232 jumper settings for JW8 or JW9 when
communicating in RS-423 mode (page 1 -9). RS-423 devices should be
unterminated and cable length should be a maximum of 50 ft.
Communication Rates