# Communication between AVR and CORUS PTZ device

12 NULL bytes are being sent to CORUS device (to power on it) with this codevision code like

putchar('\0');


Sending is ok , but regarding to page 9 of the CORUS protocol doc, the device should respond with only 3 Null bytes but it also sends different values afterwards, e.g one time 114 064, another time 255 251, and so on.

12 volts is used for the RS232 power supply, as specified on page 15 of the user guide. We've tried connecting directly both from a PC serial port and FT232R/MAX232, with the same results. Normally this would be used with an ISB to electrically isolate the signal.

Why doesn't the device respond with only three NULL bytes?