Experimental Physics and
Industrial Control System

I have a particularly tricky serial device I am working on programming. To make matters worse it has a very slow response speed to commands. 

It sends unsolicited commands, but also does normal request response messages. I am usually polling the device every 4 seconds while it is running. Very often when receiving the unsolicited commands I receive the following error:

I tried searching techtalk but cannot seem to find anyone with a similar issue. This is very problematic because this device is very slow and the unsolicited messages are the most important.  Also I should mention that all commands I receive from the device need to be acknowledged, so immediately after the "in" string in the protocol follow I have an out string with the same format. 

(Another problem I have is that if the device has messages to send very close together in timing it will group them into a single message but with an unpredictable order. I have no idea how to deal with this. I can imagine a cascading mismatch sequence but this would be very complex. Is regex the only other option? When it does group the messages they are delimited by a space, but in all other instances it is just single messages with no space. I almost need some sort of function to search for a space and if it finds it to separate the messages, but otherwise ignore the normal messages).

I'm using stream device 2-6 and asyn4-21. Unfortunately can't post the db or protocol file because I had to sign a NDA for this device. 

Thank you!