AHL (ASCII handshake lines)

The AHL instruction sets or resets the RS-232 Request to Send (RTS) handshake control lines for a modem.
Languages supported: Function block diagram, ladder diagram, structured text.
This instruction applies to the L20E, L50E, and L70E controllers.
AHL
AHL
AHL parameters
Parameter
Parameter Type
Data Type
Description
IN
Input
BOOL
Rung input state.
  • TRUE: When Rising Edge is detected, start the instruction block with the precondition that the last operation is complete.
  • FALSE: The instruction block is idle.
AHLInput
Input
AHLI
The channel to be operated, and the set or reset of the RTS control line for the modem.
Use the  AHLI data type to define the Channel, SetRts, ClrRts, and Cancel parameters for AHLInput.
Q
Output
BOOL
Indicates when the set or reset is complete.
Outputs of this instruction are updated asynchronously from the program scan. Output Q cannot be used to re-trigger the instruction because IN is edge triggered.
  • TRUE: The function block is complete.
  • FALSE: The function block is not complete.
ChannelSts
Output
WORD
Displays the current status (0000 to 001F) of the handshake lines for the specified channel.
For more information about the current status, see AHLI data type.
Error
Output
BOOL
Indicates the existence of an error condition.
  • TRUE: An error is detected.
  • FALSE: No error.
ErrorID
Output
UINT
A unique numeric that identifies the error. The errors for this instruction are defined in ABL error codes.
AHL error codes
Error code
Error description
03
Transmission cannot be completed because the Clear-to-Send signal was lost.
06
Illegal parameter was detected.
07
Cannot complete ASCII send or receive because channel configuration has been shut down using the channel configuration dialog.
08
Cannot complete ASCII Write due to an ASCII transmission already in progress.
09
ASCII communication requested is not supported by current channel configuration.
10
The Cancel was set, stopping instruction execution. No action required.
11
The requested length for the string is either invalid, a negative number, greater than 82, or 0. Applies to ARD and ARL function blocks.
13
The requested (.LEN) in the control block is a negative number or a value greater than the string size stored with the source string. Applies to AWA and AWT function blocks.
14
The ACL function block was canceled.
16
Serial port is not supporting RTS or CTS control lines.

AHL examples

AHL function block diagram example
AHL function block diagram example
AHL ladder diagram example
AHL ladder diagram example
AHL structured text example
AHL structured text example
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