Hello again, Mark.
Thank you for your advice. I apologise for the delay in replying.
I agree with you that the quickest way is to use the analog data from the analyser – everything is already set up to do that and it works well. The shortcoming is that the limited analyser DA precision means that we can see digital steps in the analog data. These are at the level of resolution we want to achieve in our measurements. When we look at the modbus data (not in HTB) we do not see these. A simple low-pass filter is of limited value when the noise on the signal is not continuously varying. When we look at the higher precision of the digital signal available through modbus then we can resolve changes in analyser readings at the level we require wihout seeing the digital steps.
I have spent many hours trying to get at the modbus communications through HTB with, so far, limited success. I have generated a modbus request string which I believe is read by the slave device but I have yet to receive a reply from it. Progress is limited by not being able to get HTB to load a virtual com port so I can’t get HTB to talk to a modbus slave simulator to see exactly what is going on.
I think my next post should be to look for help with virtual com ports – (I have com0com installed) – perhaps someone knows of one which HTB will be happy to talk to.
Thanks once again.