RS232 Hardware Handshake

[Spg]

Hello,

I have a Julabo circulator that I am trying to communicate with using RS232. The problem seems to be the hardware (flow control) handshake that is required. If I use HyperTerminal in windows and choose 4800, even, and hardware flow control everything works fine. But with LabView the options for hardware are RTS/CTS and DTR/DSR, I have tried each and neither work. I know LabView can do it because Julabo’s free utility was written in Labview. But everyone I have talked to in the US says that Germany wrote the code and the do not know how the RS232 communications work. So I am waiting for a response.

In the mean time I have been using a port sniffer to double check what I am sending in LabView against what I am sending in HyperTerminal. The commands look identicle, so I am suspecting that I do not have the hardware handshake working correctly. What is the secret to get the hardware handshake to work? It is a combination of RTS/CTS and DTR/DSR or is it just one or the other? I have been searching the net, NI and here and I cannot find any topics talking about hardware handshaking.

Bryan

[Ton Plomp]

Have you checked the LabVIEW code from germany? Or is it hidden.

BTW I think they should get you in contact with Germany, my experience is that Germans are quite good in English.

One thing to suspect is termination of the strings. Does your sniffer show the termination characters?

Ton

[Spg]

QUOTE(tcplomp @ Aug 9 2007, 10:42 PM)

Have you checked the LabVIEW code from germany? Or is it hidden.

BTW I think they should get you in contact with Germany, my experience is that Germans are quite good in English.

One thing to suspect is termination of the strings. Does your sniffer show the termination characters?

Ton

The code is an EXE, so I am not able to see anything.  

If I do not get results from the US Julabo I will contact Germany myself.

I am adding 2 screen shots of my sniffer.

_out.jpg = I used HyperTerminal to set the control to 16, next I sent a 15 command in LabVIEW (which did not work), so I sent it in HyperTerminal and it worked fine.

_in_mode.jpg = I sent the command in HT and received a response, but no response with LabVIEW.

I have tried both DTR/DSR and RTS/CTS and no luck with either.

[Ton Plomp]

Three options:

1. edit the VI to check the number of bytes ready at the serial port (that's a VISA property)
   
2. End the read on the termination charachter
   
3. Lower your number of bytes to read
   

I'd go for option 1:

http://forums.lavag.org/index.php?act=attach&type=post&id=6592

Ton

[Spg]

Hello Ton,

I received a reply from Julabo this morning with a sample vi. It turns out that they use 7 data bits, not 8. I checked my hyperterminal program and it was set to 7, I have no idea how or why it was set at 7. I thought I set it at 8.

I do like the idea of checking the bytes at port for use with reading. Currently the vi was set at 10 for bytes to read, but I am all for having the program able to figure it out for itself.

Thanks

Bryan

Edit: I added the bytes at port (option 1), I noticed that I needed to insert a 250ms wait after the data was sent for it to work properly. Is this normal? I imagine that is just the time it takes for the unit to respond....

[draco]

QUOTE(Spg @ Aug 10 2007, 05:57 PM)

Hello Ton,

I received a reply from Julabo this morning with a sample vi. It turns out that they use 7 data bits, not 8. I checked my hyperterminal program and it was set to 7, I have no idea how or why it was set at 7. I thought I set it at 8.

I do like the idea of checking the bytes at port for use with reading. Currently the vi was set at 10 for bytes to read, but I am all for having the program able to figure it out for itself.

Thanks

Bryan

Edit: I added the bytes at port (option 1), I noticed that I needed to insert a 250ms wait after the data was sent for it to work properly. Is this normal? I imagine that is just the time it takes for the unit to respond....

please can you post this sample *.vi from julabo?

i have the same problem with a julabo thermostate; but in c++.

i get no answer from the thermostate.

so i hope the *.vi will help me .....

many THX

ps.: if there is anyone with a solution in c++, i will very interested to see the code.