this is a little ambiguous.
Header Type Length Report ID Data Check Sum...Makes sense if you put commas in the right place
Header Type, Length, Report ID, Data, Check Sum.
If that was the case then a msg with no data would be something like
7E 03 02 18 9B
Is this your interpretation or is it stated as such? Usually a checksum is a CRC. if it is a CRC-8 (there are a number of 1 byte CRCs) then the last value would be 0x29 rather than 0x9B, for example.
If you know there are no more bytes in the buffer, then you can ignore that error. That is, if the packet size is fixed, and you are receiving correctly, you don't have to reach the timeout. Also, you can set the timeout to a value less than 10 seconds, if you know that all transactions occur before the time is up.
Tried your software... It's for an different version UPS and the protocols are different. That said I just modified your software with the current protocol commands and I get the same results, read function times out.
I'm leaning toward my problem is not software related, but hardware. Probably the USB to RS-232 converters I'm using. I just had a wild thought and tried to connect to the UPS using my USB to RS-232 converter and their PowerAlert software. Of course there are variables they ask you to select the communications protocol and the protocol they sent me (4001) isn't listed out of the probably 30 protocols in their dropdown. I selected a couple that sounded right but I can't connect with their software on this port either.
I'll ohm out the cables they sent to see if anything looks bad.
Thanks for looking and trying.. It's just really hard working from home without the proper resources to get the job done.
Ok... I've always said there are no stupid questions... It's protection for me when I ask that stupid question....
I looked on the back of the unit and there is only one DB9.
You're right about the "dry contact" connections. They are confusing, but Tripp-Lite tech support assures me I can communicate serial on the DB9 connector.
I agree, the manual, protocol documentation and tech support for purposes of software aren't very helpful.