Comment 5 for bug 841084

I added a "print" statement before line 164.

            print "---->",b
            p = struct.pack(fmt, PACKET_FRAME, struct.calcsize(fmt), 0, PACKET_TYPE_COMMAND, command,
                             0, 0, operation, 0x0f, *b)

I got the following output :

----> (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 36) # First call to function. At start-up
----> (0, 0, 0, 16, -6, 2, 16, -6, 2, 16, -6, 2, 36) # Second call to function. Negative numbers result in an error.

So the calibration paramaters are negative, and this gives and error.

struct.error: ubyte format requires 0 <= number <= 255

Regards

Peter