Read RTS and DTR pin logic states with Synaser (on Windows)

[Kepsz]

Hi,

In Synaser, we can read the logic states of DSR and CTS pins, but not RTS and DTR.
RTS and DTR pin logic states can only be written by using the EscapeCommFunction, that is declared in redef.inc

In redef.inc, we have this: DeviceIoControl, that in theory can access to the logic states of RTS and DTR pins.


I tried to test it in this very basic code:

Code: Pascal  [Select][+][-]

1. function TBlockSerial.GetRTSF;
2. var
3.   iostatus, tmp: DWORD;
4.   testlw: longword;
5.   olp: POVERLAPPED;
6.  
7. begin
8. {$IFNDEF MSWINDOWS}
9.  
10. {$ELSE}
11.   DeviceIoControl(FHandle, 1769592{IOCTL_SERIAL_GET_DTRRTS}, @testlw, 0, @iostatus, sizeof(iostatus), @tmp, @olp);
12.   result := true;
13. {$ENDIF}
14. end;

But the problem is IOCTL_SERIAL_GET_DTRRTS is a macro, that is only defined in ntddser.h header file. https://doxygen.reactos.org/d5/d2e/ntddser_8h_source.html#l00056 1769592 is a value for that according to chatgpt, but it is deffinitly wrong.

Is there a way to get use that macro? Or is it defined in some unit?
Or is there a better way to get the logic states of those pins?

More info:
https://stackoverflow.com/questions/59408368/getting-dtr-and-rts-pin-of-serial-port-in-c-on-windows-platform
https://learn.microsoft.com/en-us/windows/win32/devio/calling-deviceiocontrol

[marcov]

My own calculation comes out on 2064384.

Parameterized compiletime macros can't be used as is, but sometimes you can write a function for them to calculate them.

[Kepsz]

Both values have the same result in iostatus. I guess it is simpler to store the RTS / DTR IO logic values in variables when the write function sets them.

[MarkMLl]

In Synaser, we can read the logic states of DSR and CTS pins, but not RTS and DTR.
RTS and DTR pin logic states can only be written by using the EscapeCommFunction, that is declared in redef.inc

FPC is cross-platform, and in the general case those pins are output-only.

MarkMLl

[Jurassic Pork]

 

[Kepsz]

It is done with LazSerial? LazSerial has the mentioned functionality but I had to implement this in a quite complex app that built around synaser.

Jesterday I was able to implement this into synaser, it is working.

[Jurassic Pork]

It is done with LazSerial? LazSerial has the mentioned functionality but I had to implement this in a quite complex app that built around synaser.

Hello,
if your project is a GUI project may be you can use LazSerial because TBlockSerial  is a part of the TLazSerial component :

Code: Pascal  [Select][+][-]

1.  TLazSerial = class(TComponent)
2.   private
3.     FActive: boolean;
4.     FSynSer: TBlockSerial;
5.     FDevice: string;  

but if your project is a console project use synaser.   TLazserial is an event driven component.

Friendly, J.P

[Kepsz]

It is done with LazSerial? LazSerial has the mentioned functionality but I had to implement this in a quite complex app that built around synaser.

Hello,
if your project is a GUI project may be you can use LazSerial because TBlockSerial  is a part of the TLazSerial component :

Code: Pascal  [Select][+][-]

1.  TLazSerial = class(TComponent)
2.   private
3.     FActive: boolean;
4.     FSynSer: TBlockSerial;
5.     FDevice: string;  

but if your project is a console project use synaser.   TLazserial is an event driven component.

Friendly, J.P

Yeah, it is a quite complex gui app with threading for the best possible serial troughput.
But storing RTS and DTR IO states locally in Synaser works great, I will recommend them to implement this feature.