These two documents describe the protocol used for both the network and the serial devices manufactured from Micrelec Electronics:
Also here is the official specification document:
- ΠΟΛ 1257 (Greek)
At least at the following urls you can find an emulator of Signature devices manufactured from Micrelec.
It's better to get the one from Synthex since it supports the network device as well. Actually the development of the library is based on that emulator.
Also of great interest is the implementation of the communication library from Micrelec in C language.