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


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?

Alternative links: protocol guide

  • \$\begingroup\$ Please don't use salutations or signatures on your posts. \$\endgroup\$ – Kevin Vermeer Nov 29 '11 at 21:04
  • \$\begingroup\$ How is the device connected to the atmega? Does it speak RS232 or logic level serial? Did you use a level shifter/inverter chip? Do you have the right baud rate? Do you know for a fact that putchar() is writing characters to the serial port? \$\endgroup\$ – Chris Stratton Nov 30 '11 at 3:42
  • \$\begingroup\$ @Chris Stratton Thanks sir, as mentioned in my first post , at page 15 of catalog ,device has RS232 port (it seems we need MAX232 yes?) and in that page buad rates are noticed also ,when he uses MAX232 we get that result mentioned in first postand without max232 no result .so coder is a pro coder ,don't seem this be a coding issue. \$\endgroup\$ – dehqan Nov 30 '11 at 4:38
  • 1
    \$\begingroup\$ The first rule of debugging is to check your assumptions. Take measurements. Test against other equipment. And don't assume that a "pro coder" is skilled at embedded systems. Lots of embedded systems work gets done with one hand on the keyboard and the other holding a scope probe. \$\endgroup\$ – Chris Stratton Nov 30 '11 at 9:23

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