in reply to: Time datatype posted by Jens on 24 July 2012 at 14:27:23.
As far as I can see from the specs, for HART 7 you do have to include a real-time clock! It does not have to be settable (so may not represent actual clock time), but must roll over every 24 hours. It doesn't seem to say how accurate this must be, but if it is wildly out, it isn't clear how you can implement the 24-hour rollover.
Maybe there should be an option to return a *not used* value in command 9. Or you might get away with returning a time of 0, with the warning response code 8 (Update Faiure).
For a properly accurate clock, since time data is to be a 32-bit number counting in 1/32 of a millisecond, I make that 32000 x 60 x 60 x 24 = 2764800000, or roll over to 0 after 2764799999, or A4CB7FFF in hex.