Cheat Engine

[Polynomial]

I'm writing a POS system which will be used in small businesses, mainly targeted at standard Windows desktops and embedded retail POS machines. On the POS side, there is usually a VFD module (example) on the customer facing side. Most follow a standard communications protocol over the serial port. For example, "\x02\x0aL1Hello!\x03" would set the top row to "Hello!".

However, not all modules follow this rule. The spec sheets and such aren't so useful in this case, and I can't afford to buy the modules myself in order to sniff the COM traffic. Does anyone know of somewhere where I can find all the communication specs for the most commonly used VFD modules?