SHACKBUS Protocol

Protocol

What is the most simple and most common ? Of cause RS232 serial communication!

So, SHACKBUS uses serial asynchroneous data to communicate between controller and devices.

SHACKBUS uses a rate of 9600 baud, 8 data bit, no parity, 1 stop bit on the bus.

+5 volt is the idle state (stop bit polarity) and 0 volt is the start bit polarity. (see 'electrical')

All communication uses ASCII characters.

A command line consists of four parts:

One asterisk (* = h2A) as first character, marking the beginning of a command string.

Two address Bytes (Uppercase and figures only)

a command string (variable syntax and length) which contains no <CR> or asterisks.

a RETURN character (<CR> = h0D)

Commands are transmitted from the controller to all devices, but only the one device which matches both address bytes will react and respond.

Every device adress must be unique within one bus system.
Devices must not access the bus without being individually adressed / polled by the controller (PC).
If a device is properly adressed, it must react within 1 second after the controller terminates the command and reply.
ANY commands with the matching adress must be acknowledged - at least by sending an error message.