Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 46)

Chapter
Using the Communication Ports 2
2 -8
ASCII Port
If you set JW4 to one of the configurations shown at the left, PRT1 and/or
PRT2 are ASCII ports (asynchronous serial communication channels)
compatible with RS-232C, RS-422, RS-485 interfaces. When you
configure PRT1 and PRT2 as ASCII ports, you use jumpers JW8 and JW9
(page 1 -9) to select an electrical interface. The RS-485 electrical
interface is not the same as the DH-485 network (the electrical interface is
similar but the DH-485 network has embedded firmware to control
communication). Through the ASCII ports you can interface with:
printers
terminals
commercial asynchronous modems
To interface with these devices, use either bi-directional XON and XOFF
software handshaking or RTS/CTS, DTR, DSR, DCD hardware
handshaking.
Use the MODE command (page 11 -20) to change ASCII port
configuration. You can also use CALL 30 (page 12 -20 ) to change the
ASCII port configuration for PRT2 only.
The ASCII port has these parameters:
Port parameters Selections Default settings
communication rate 300, 600, 1200, 2400, 4800, 9600, 19200 1200
parity none (N), even (E), odd (O) N
number of data bits 7 or 8 8
number of stop bits 1 or 2 1
handshaking no handshaking (N)
software handshaking (S)
hardware handshaking (H)
hardware and software handshaking (B) S
storage type store information in user ROM and RAM (E)
store information in battery backed RAM (R) R
When you select 8 bits/character you have full access to all 8 bits of each
character on both input and output data bytes.
JW4 ASCII Port Configurations
PRT1 and PRT2 ASCII
Only PRT2 ASCII
Only PRT2 ASCII