COMMERCIAL IN CONFIDENCE
Page 18
2. Write the Setpoint value
The setpoint value must be sent in the same units as are currently displaying on the controller, that is,
in Degrees Fahrenheit, if selected, otherwise in Centigrade. The value to be transmitted must be an
integer number of 10ths of a degree. For example, to transmit a value of 432.1 degrees, the setpoint
register must be set to 4321 (decimal) which is 10E1 (hex). The following message writes the setpoint,
in this example xx would be 10 (hex) and yy would be E1 (hex).
byte 0 : Slave address xx
byte 1 : Function code (write register) 06 hex (always)
byte 2 : Register Address high byte 00 hex (always)
byte 3 : Register Address low byte 7F hex (always)
byte 4 : Setpoint Value high byte xx
byte 5 : Setpoint Value low byte yy
byte 6 : CRC low byte ??
byte 7 : CRC high byte ??
3. Exit program mode
A two part sequence, similar to the enter program mode sequence is required to accept the new values
and unlock the controller keypad. Similarly, both messages must be present in strict sequence for the
values to take effect.
1st Message:
byte 0 : Slave address xx
byte 1 : Function code (write register) 06 hex (always)
byte 2 : Register Address high byte 03 hex (always)
byte 3 : Register Address low byte 00 hex (always)
byte 4 : Register Value high byte 00 hex (always)
byte 5 : Register Value low byte 06 hex (always)
byte 6 : CRC low byte ??
byte 7 : CRC high byte ??
The controller should reply with an identical response, if not, this message should be re-
transmitted until the response is correct.
Note: the 9500 does not require the security message to be sent.
2nd Message:
byte 0 : Slave address xx
byte 1 : Function code (write register) 06 hex (always)
byte 2 : Register Address high byte 16 hex (always)
byte 3 : Register Address low byte 00 hex (always)
byte 4 : Register Value high byte 00 hex (always)
byte 5 : Register Value low byte 00 hex (always)
byte 6 : CRC low byte ??
byte 7 : CRC high byte ??
The CAL Controller should reply with an identical response, if not, the message pair is lost and
the exit program mode sequence must be repeated from message 1.
Any changes made will only take effect on receipt a valid exit program mode sequence - if the
controller is de-powered before this sequence is completed, the previously stored values will be used.
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