Setting up RS232 Comms Port

[David Higgs]

In my application I would like VFP to communicate with a Transceiver via the RS232 Comms Port. The information exchange is occasional and very short bursts. Basically a "FA;" command is sent to the transceiver which produces a reply of "FA14250000"; this is typical of what I am trying to achieve.

I have used a small third party comms utility to check that the comms port is working ok, now I need to set up VFP comms but not too sure where to start. I understand MSCOMM32.OCX has been used but I have no idea on how to set this up or incorporate it with VFP.

Any help would be most appreciated.

Regards,
David

 

[Olaf Doschke]

How about this?

https://support.microsoft.com/en-us/kb/154741

Bye, Olaf.

 

[David Higgs]

Ok, progress so far.

I now have a form with MSCOMM32.OCX set up called "mycom" and have a Command Button with the following code in the Click Event.

thisform.Mycom.output = "FA;"	&&	Send request to FT-2000 Transceiver to read "Frequency"

ft2000_freq = thisform.mycom.Input

		freq = SUBSTR(ft2000_freq,3,8)
		freq = Transform(freq,"@R 99.999.999")
		
IF LEFT(freq,1) = "0"			&&	Remove leading Zero
		freq = SUBSTR(ft2000_freq,4,7)
		freq = Transform(freq,"@R 9.999.999")
ENDIF

thisform.label1.Caption = (freq)	&&	Display Frequency on Form

The above code is communicating (both ways) with the Transceiver, however it takes two clicks of the button to actually read and display the Frequency. I guess I need to look at a "Receive Buffer"?


Regards,
David

 

[Olaf Doschke]

You can't expect Input directly coming in.
Please reread

https://support.microsoft.com/en-us/kb/154741

it shows when to read Input.

You can somewhat use this comm control as is, but to make use of the events you have to put code in there, so you better create a class based on oleconrol and pick the communications control.

This is asnchronous, you only set output and input will cause oncomm events. You receive input there, not in the code you output.

Bye, Olaf.

 

[David Higgs]

Hello Olaf,

Thank you for your reply.

I've read and re-read the document but couldn't help feeling that it was a bit of an overkill for my application. As I said, basically send / receive is working, it was just a case looking at the receive buffer too soon.

I've decided to insert a "10ms timer" to give the Transceiver time to respond to the request.

DECLARE Sleep IN Win32API INTEGER nMilliseconds
Sleep(10)

Source of the code

http://www.tek-tips.com/viewthread.cfm?qid=688872

Probably not the most efficient way of doing things but it appears to do what I want.


Regards,
David