Hach sc200 4-20 User Manual page 9

Troubleshooting calibration failure
Calibration failures normally occur when one or more values in the system
are outside of expected limits. A common cause of calibration failure is the
existence of a large difference between expected and actual values. This
difference may be due to a signal drop in the lines or another cause. This
troubleshooting procedure often resolves calibration failures.
1. Output a 4 mA signal from the outside device. (Refer to the instructions
for the outside device for more information.)
2. Use a digital multi-meter to make sure the signal is 4 mA. The best
place to connect the multi-meter is on the bare spots of the output wire
leads just before they attach to the input card.
3. If the output signal is not 4 mA, calibrate the signal at the output device.
4. Change the output to 20 mA and perform the same output device
calibration.
5. After the output device is calibrated, attach the output wires to the 4-20
mA input on the controller.
6. Output a 4 mA signal from the outside device, and calibrate the
controller 4-20 mA input to that value.
7. Output a 20 mA signal from the outside device, and calibrate the
controller 4-20 mA input to that value.
8. Verify the calibration using a 12 mA signal.
Module diagnostics and tests menu
1. From the Settings Menu, select Sensor Setup.
2. Select Diag/Test.
3. Select an option and push the ENTER key to view the data.
Option
Module information
Description
Software version
Bootloader version
Driver version
Serial number
Option
Signals
Cal data
Sensor diagnostics
1. From the Settings Menu, select Sensor Diag.
2. Select Error List, Warning List or Event List and push ENTER to view
the data.
3. Push ENTER to return to the Sensor Diagnostics menu.
Description
Current (mA)
Count
Cal point 1
Cal value
Cal point 2
Cal value
Offset
Slope
English 9