Aalborg Vortex - Manual (Page 71)

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6.1.1 Initial setup
Power up the Vortex Flow Meter for at least 15 minutes prior to commencing the
calibration procedure. Make sure absolutely no flow takes place through the meter.
Establish digital RS-485/RS-232 communication between PC (communication ter-
minal) and Vortex flow meter. The commands provided below assume that cali-
bration will be performed manually (w/o Aalborg
® supplied calibration and mainte-
nance software) and the device has RS-485 address 11. If Aalborg ® supplied cali-
bration and maintenance software is used, skip the next section and follow the
software prompts.
Enter Backdoor mode by typing: !11,MW,1000,1[CR]
Unit will respond with: !11,BackDoorEnabled: Y
Disable DAC update by typing: !11,WRITE,4,Y[CR]
Unit will respond with: !11,DisableUpdate: Y
where: [CR] Carriage return character
(equals pressing Enter key on the PC key board).
6.1.2 Analog 4-20 mA channel#1 output calibration
1. Connect a certified high sensitivity multi meter set for the current
measurement to pins 1 (+) and 2 (-) of the TB3 terminal connector.
2. Write 4000 counts to the DAC1 channel: !11,WRITE,0,4000[CR]
3. Read current with the meter and designate it to Reading_4000_mA variable.
4. Write 400 counts to the DAC1 channel: !11,WRITE,0,400CR]
5. Read current with the meter and designate it to Reading_400_mA variable.
6. Calculate Out1_Scale_mA value:
Out1_Scale_mA = 3600 / (Reading_4000_mA - Reading_400_mA)
7. Calculate Out1_Offset_mA value:
Out1_Offset_mA = - (Reading_4000_mA/10 - Reading_400_mA) X Out1_Scale_mA
8. Save Out1_Scale_mA in to the EEPROM: !11,MW,32,Y[CR]
Save Out1_Offset_mA in to the EEPROM: !11,MW,33,Z[CR]
Where: Y – the calculated Out1_Scale_mA value.
Z – the calculated Out1_Offset_mA value.