CAL Controls 3300 Communications Manual page 18

Writing the Setpoint
Writing to the CAL Controller requires a three stage process which prevents simultaneous access from
the front panel. To prevent accidental changes caused by unreliable communications, a sequence of
messages must be sent in strict order.
1. Lock the keypad - a sequence referred to as enter program mode
2. Write new values to the CAL Controller
3. Unlock the keypad and restart with the new values - a sequence referred to as exit program
mode
1. Enter Program Mode
To enter the programming mode of the CAL Controller, two messages must be transmitted - both must
be recognised, in strict sequence, as valid for the operation to be successful. The first message
informs the controller that the next message is a security locking message, if the second message is
not acknowledged correctly, the whole sequence must be re-started from message 1.
1st Message:
byte 0 :
byte 1 :
byte 2 :
byte 3 :
byte 4 :
byte 5 :
byte 6 :
byte 7 :
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 :
byte 1 :
byte 2 :
byte 3 :
byte 4 :
byte 5 :
byte 6 :
byte 7 :
The CAL Controller should reply with an identical response, if not, the message pair is lost and
the sequence must be repeated from message 1.
COMMERCIAL IN CONFIDENCE
Slave address
Function code
Register Address high byte
Register Address low byte
Register Value high byte
Register Value low byte
CRC low byte
CRC high byte
Slave address
Function code
Register Address high byte
Register Address low byte
Register Value high byte
Register Value low byte
CRC low byte
CRC high byte
Page 17
xx
(write register) 06 hex (always)
03 hex (always)
00 hex (always)
00 hex (always)
05 hex (always)
??
??
xx
(write register) 06 hex (always)
15 hex (always)
00 hex (always)
00 hex (always)
00 hex (always)
??
??