Thats a good solution if you dont want to mess around with protocols. Its been a few years but....
I used a TI Basic module with a RS422 converter to the serial port of the SLC504. I had to play around with pinouts and built my own cables which took longer than I wanted. I ran it at...
From the info you have provided, It points toward issues unique to your system.
1. Get your batteries replaced.
2. Get the major/minor fault codes after a failure.
3. From info you provided, I believe there can only be 3 possible issues: programming issue ( math overrun), bad power, or...
