KROHNE UFC 500 HART - Manual (Page 38)

HARTô Smart Communications Protocol
UFC500 Command Specification Rev: 2.0 Release Date: 9 Jun 2001
© 2001 KROHNE Mefltechnik D-47058 Duisburg Page 38
8.19 Command #151 Control Zero Calibration
Unlike Command #43, Set Primary Variable Zero, where an instant measurement is used to correct zero point, this
command performs calibration exactly as if this process was activated via device keypad (Menu 3.3): 255 subsequent
measurements are averaged before zero correction is done. The process lasts 3.5-5.5 sec (best and worse cases).
REQUEST DATA BYTES
#0
CAL
CONTROL
VAR
RESPONSE DATA BYTES
#0 #1 #2 ... #5
CAL CAL CAL CAL
CONTROL STATUS ZERO ZERO
VAR VALUE VALUE
MSB LSB
Data Byte #0 Calibration control variable:
0 - Exit calibration,
1 - Start calibration,
2 - Store calibration value,
3 - Get calibration status.
Data Byte #1 Calibration status:
0 - No ìfreshî calibration data,
1 - Calibration is active or is over.
Refer to the note below.
Data Byte #2-#5 Zero value, IEEE 754, in % of Upper Range Value for forward flow.
NOTE: After a StartCalibration request is accepted, the device is triggered into a ìBusyî mode, that lasts about 20
seconds. All the telegrams received within this period will be rejected with the ìBusyî Response Code (32). During
calibration process the device can be polled with Command #151 with CalibrationControl set to м3о (Get calibration
status). The first non-singular reply will supply master with calibration result. The obtained zero value is preserved in
RAM until Command #151 will be received with ExitCalibration, StartCalibration or StoreCalValue value of control
variable.
NOTE: A request to StoreCalValue when the CalibrationStatus is zero, will not cause any transmitter action.
COMMAND-SPECIFIC RESPONSE CODES
0 No Command-Specific Errors
1 Undefined
2 Invalid Selection (Of Control Variable)
3-4 Undefined
5 Too Few Data Bytes Received
6 Local Device User
7 In Write Protect Mode
8-127 Undefined