Long Term Instrument Data Acquisition With Python - Using "while" Loops And Threaded Processes

I will have 4 hardware data acquisition units connected to a single control PC over a hard-wired Ethernet LAN. The coding for this application will reside on the PC and is entirely

Solution 1:

I'm thinking that it would be good for you to use client-server model

It would be nicely separated, so one script would not affect the other - status check / data collecting

Basically what you would do it to run server for data collecting on the main machine, which could have some terminal input for maintenance (logging, gracefull exit etc..) and the data collecting PC would act like clients with while True loop (which can run indefinetly unless killed), and on each of data collecting PC would be server/client (depends on point of view) for status check and that would send data to MAIN pc where you would decide what to do

also if you use unix/linux or maybe even windows, for status check just use ssh to the machine and check status (manually or via script from main machine) ... depends on specific needs...

Enjoy

Solution 2:

You may need more than one loop. If the instruments are TCP servers, you may want to catch a 'disconnected' exception in an inside loop and try to reconnect, rather than terminating the instrument thread permanently.

Not sure about Python. On C++, C#, Delphi, I would probably generate the wait by waiting on a producer-consumer queue with a timeout. If nothing gets posted, the sequence you outlined would be repeated as you wish. If some of that other, occasional, stuff needs to happen, you can queue up a message that instructs the thread to issue the necessary commands to the instruments, or disconnect and set an internal 'don't poll, wait until instructed to reconnect and poll again' flag, or whatever needs to be done.

This sort of approach is going to be cleaner than stopping the thread and connecting from some other thread just to do the occasional stuff. Stopping/terminating/recreating threads is just best avoided in any language.