Page 4-8
Airnet II Particle Sensor Operations Manual
Chapter 4
4-20 mA Signal Configuration / Operation
Adjusting the 4-20 mA Outputs
The 4-20 mA outputs can be adjusted to compensate for normal variations in the
electrical components. The 4-20 mA outputs are only guaranteed to be /- 0.2
mA (1% full scale) without any adjustment.
Each of the three 4-20 mA outputs can be adjusted separately. A current meter must be
connected to the 4-20 mA output to be adjusted.
To adjust a 4-20 mA output, connect to the setup interface of the sensor:
1.
Issue the command
current adjust
.
2.
The operator will be prompted for the index of the 4-20 mA output to be adjusted
(Output Channels 1-3 are indexed 0-2). The offset and scale factors for the selected
output will be set to 0 and 1 respectively.
3.
The sensor will then apply 4 mA to the selected output. The operator will be
prompted to enter the actual reading as measured by the current meter. The unit
will automatically calculate the appropriate offset factor to be applied to that
output.
4.
The sensor will then apply 20 mA to the selected output. The operator will be
prompted to enter the actual reading as measured by the current meter. The unit
will automatically calculate the appropriate scale factor to be applied to that
output.
5.
The operator will be prompted to enter "
y
" to accept the channel adjustment. If
accepted, the new offset and scale factors will be saved. Whether accepted or not,
the unit will reboot and restart normal operation.
