VB6 MSCOMM wroks on one PC and not another

[cooksydesign]

I have been using MSCOMM for quite awhile, this problem has dah me stumpped for a week now.
Properties of MSCOMM:
DTREnable is True
EOFEnable is TruHandshaking is 0
InBufferSize is 3072
InPutMode is 0
OutBuffSize is 512
RThreshold is 1
RTSEnable
Settings is 2400, N,8,1
SThreshold

Using the same PIC code and same VB code on different machines, I get different results. The only machine that the code operates correctly on is an older machine, x86, Windows 2000 SP2. A second machine running Win2K and a third machine running XP have this problem;
MSCOMM receives the first 8 characters, processes these 8 characters, then receives the balance. I am testing with 10 characters. I am sending PIC variables from a bit array. I am receiving the data in VB as a srting.
I have sent the data to HyperTerminal and in every case the correct data is being sent from the PIC. For some unknown reason, on certain machines all the data is not received into the buffer.
In addition to the slower processor I mentioned ealier, the copy of VB on the slower machine does not have the latest service pack while the other machines do, SP6. Attempting to load SP6 causes some errors and does not load. I don't have the errors handy.
I have places a Pauseus in the Send routine thinking the slower processor was the issue, but no change.
Any suggestions are appreciated.

B

[T.Jackson]

What do you have the attribute InputLen set to?

[cooksydesign]

Thanks for the responce. Input Length is set 0.

I have since sent the input string to a label, visable property set to false, and so far every test I have done, not extensive mind you but progress, has been successful. I don't why the program operates better this way, timing I'm guessing.

If InputLen should be something other than 0 please let me know. The input length is variable, no telling how many characters.

Thanks again for the interest.

B

[T.Jackson]

Thanks for the responce. Input Length is set 0.
If InputLen should be something other than 0 please let me know. The input length is variable, no telling how many characters.

For Win XP & 2K2 you definitely want InputLen set to anything other than 0. I lost some hair a few years back when I wrote a piece of software for a serial io controller, worked fine on 9x with InputLen set to 0, but refused to work on XP until I changed it to equal 1.

[cooksydesign]

Again, thanks for the interest in my post. Changing the receive length property to 1 did not do any good. I think that tells MSCOM buffer what to expect. If the incoming string was a fixed length it may have helped. I seem to have sorted it out by sending the string to a label first, then work with the data. It has not failed since I started doing it that way. I realize this is a work around, and the true cause is not identified. If there are other suggestions, I will most certainly try them.

Regards.

B

[mister_e]

I no longer use MsComm and VB6, i use VBExpress or .Net. From there you can also use the LF interrupt events (comport.ReadLine) which is probably the way to go. Never ever failed for me 'till now. VB6 EOF event is one method... if you can make it work.

LF event... way easy to code on the PIC side... hserout [whatever, 10]

There's a lot of different way to have success with VB, i have some applications dealing with MBs and GBs of data transfer... problem-free since years now. Even in VB6.

I prefer the handshaking method... hardware or software.... and a preamble string never bite anyone yet.