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7.3.1 Initial Setup
Power up the Mass 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 (communi-
cation terminal) and XFM. The commands provided below assume that calibra-
tion will be performed manually (w/o Aalborg® supplied calibration and mainte-
nance software) and the device has RS-485 address 11. If Aalborg® supplied cal-
ibration 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,D[CR]
Unit will respond with: !11,DisableUpdate: D
7.3.2 Gas flow 0-5 Vdc analog output calibration
1. Install jumpers J7A, J7B and J7C on the PC board for 0-5 Vdc output (see Table VI).
2. Connect a certified high sensitivity multi meter set for the voltage measurement to the
pins 2 (+) and 1 (-) of the 15 pins D connector.
3. Write 4000 counts to the DAC channel 1: !11,WRITE,1,4000[CR]
4. Read voltage with the meter and calculate:
5. Save FlowOutScaleV in to the EEPROM: !11,MW,25,X[CR]
Where: X – the calculated AoutScaleV value.
7.3.3 Gas flow 4-20 mA analog output calibration
1. Install jumpers J7A, J7B and J7C on the PC board for 4-20 mA output (see Table VI).
2. Connect a certified high sensitivity multi meter set for the current measurement to
pins 2 (+) and 1 (-) of the 15 pins D connector.
3. Write 4000 counts to the DAC channel 1: !11,WRITE,1,4000[CR]
4. Read current with the meter and calculate:
5. Write zero counts to the DAC channel 1: !11,WRITE,1,0CR]
6. Read offset current with the meter and calculate:
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