computer communication with PMAC

Thanks to some tips here I have a dll that can communicate with the PMAC over ssh. Things generally work but occasionally fail. So I wrote a test program to do 10,000 individual variable reads. I turned on echo 7 so normally when I do a read I pass a variable name, say "scan_distance_mm/n" and it will return "scan_distance/r/n/123.4/r/n/6/r/n" so I use '/6/r/b' as the terminator and keep reading until I see that (or timeout). Sometimes I will just see the value "123.4/r/n/6/r/n" instead of the echoed command. Sometimes I will just see the terminator.

One theory is that when the PMAC is busy it may not reply correctly. So my plan is to add up to 3 automatic retries, each with a 1ms sleep. But I would like to know that the behavior I'm seeing is expected not some kind of bug in my code or a physical connection issue.

I would expect “pure” SSH communications to be very robust. You should try the PDK for comparison. There is a trial version on the website:

http://www.deltatau.com/DT_Products/SoftwareDetails.aspx?CatID=500-POWER%20PMAC%20DEVELOPMENT%20KIT