User manual

IEC61131 User and Reference Manual
April 22, 2008
266
dtroff
Control DTR
Description
The dtroff function provides a way of controlling the DTR signal for a specific serial port.
When the state input is set to TRUE DTR for the serial port is de-asserted. DTR is constantly
turned off when the state input is set to TRUE.
When the state input is set to FALSE DTR for the serial port is asserted. The DTR signal is
not constantly asserted. It is asserted on the transition from TRUE to FALSE on the state
input. Since DTR is not constantly re-asserted other programs will be able to control the
DTR setting. This way other function blocks and programs will be able to control the DTR
settings.
comX
state
dtroff
Q
Arguments
Inputs
Type
Description
comX
Integer
Serial Communication port to control DTR.
Valid values are 1 to 4.
state
Boolean
Set to TRUE to force DTR off.
Set to FALSE to relinquish control of DTR.
Outputs
Type
Description
Q
Boolean
TRUE if comX input is valid.
FALSE in all other cases.