Allen-Bradley Logix5000 Reference Manual page 587

ASCII Serial Port Instructions (ABL, ACB, ACL, AHL, ARD, ARL, AWA, AWT)
Description:
The AHL instruction can do the following:
· Obtain the status of the control lines of the serial port
· Turn on or off the data terminal ready (DTR) signal
· Turn on or off the request to send signal (RTS)
Follow these guidelines to program the AHL instruction.
1. Configure the serial port of the controller.
If your application
Uses ARD or ARL instructions
Does not use ARD or ARL instructions Select either System or User mode
2. Use the following table to select the correct values for the ANDMask and
ORMask operands.
To turn DTR
Off
On
Unchanged
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Then
Select User mode
And turn RTS Enter this
ANDMask value
Off 3
On 1
Unchanged 1
Off 2
On 0
Unchanged 0
Off 2
On 0
Unchanged 0
Chapter 17
And enter this
ORMask value
0
2
0
1
3
1
0
2
0
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