Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 210)

Chapter
Call Routines 0–68 12
12 -20
Use this routine to set up the parameters for the PRT2 port.
The parameters you set are the number of bits/word, parity enable or
disable/even or odd, number of stop bits, and handshaking (software,
hardware, or none). The default communication rate is 1200 bit/s (jumper
selected) and the default start bit is 1 (fixed).
You can also use the MODE statement (page 11 -20) to set PRT2 port
parameters.
Important: From the factory, software handshaking is enabled for PRT2.
If you change this or any other PRT2 port parameter through a CALL 30 or
MODE statement and a execute PROG1 or PROG2, then the configuration
you selected with the CALL 30 or MODE statement is the power on
default. On power up the receive and transmit buffers are cleared.
The 1771-DB Series A, Rev. E added a RTS control mode to CALL 30.
This RTS control mode enabled the RTS signal and the RS-422 output pin
on each character transmitted. The 1771-DB Series B automatically
activates the RTS line any time a character is transmitted and deactivates
RTS after the last character exits the port. This feature allows RS-422
multi-point or point-to-point to function properly when hardware
handshaking is disabled.
Input and Output Arguments
This routine has six input and no output arguments. The input arguments
are (in this order):
Parameter Selections
①
number of bits/word 5, 6, 7, 8
parity enable 0=None, 2=Even, 1=Odd
number of stop bits 1=1 Stop Bit, 2=2 Stop Bits, 3=1.5 Stop Bits
software handshaking 0=None, 1=XON-XOFF
hardware handshaking 0=CTS, DCD and DSR ignored
1=CTS, DCD and DSR used for handshaking
dummy argument (optional)
②
ignored (Series A compatibility)
①
Default conditions are controlled by settings when PROG1 or PROG2 is executed
②
Dummy argument is for 1771-DB Series A compatibility. It is not required for 1771-DB Series
B operation. If it is used, the 1771-DB Series B simply ignores it.
CALL 30: PRT2 Port
Support Parameter Set