Cooper Instruments & Systems DFI 1650 Multi-Channel Digital Force Indicator - Manual (Page 51)

CF 66 45 Rev. C 2/05
11.8 Troubleshooting
11.8.1 Error Messages
See “Error Messages” in Chapter 17 for information relating to error messages.
11.8.2 Common Problems and Solutions
Erratic Display
Check electrical connections for continuity and the transducer’s wiring code from its Certificate of Calibration.
Make sure that the displacement on the transducer is constant.
Check the input to the (+)Signal (“+SIG”) and (-)Signal (“-SIG”) pins with am RMS voltmeter in its “AC Voltage”
mode. Using a voltmeter in its DC Voltage mode will always display 0.
+OVLD or –OVLD on Display
Indicates that the voltage across the (+)Signal (“+SIG”) and (-)Signal (“-SIG”) pins is overranging or underranging
the amplifier circuit. Make certain all wires are connected properly, the CALIBRATION DATA-FULL SCALE VRMS”
menu item is set correctly, and that a calibration has been performed per “Calibration Procedure”.
If you move the armature back to its electrical null point and you still see this message, the (+)Excitation (“+EXC”)
or (-)Excitation (“-EXC”) pins may be shorted to the (+)Signal (“+SIG”) and (-)Signal (“-SIG”) pins.
Analog Output Incorrect
Make certain of the type of Analog Output (voltage or current) that the channel is equipped with; see “Identifying the
Output Type”.
Use the DIAGNOSTICS->DAC FULL SCALE and DIAGNOSTICS->DAC ZERO SCALE menu items to force the
Analog Output to a known output. Then, adjust your readout device, panel meter, PLC or data acquisition system
to match.
Check the output selection jumpers; see “Output Selection”.
Auxiliary Function Pins Not Operating
Make sure that the AUX1 FUNCTION or AUX2 FUNCTION SETUP menu items are set correctly; if they are set to
DISABLED then they will not operate.
The Auxiliary Function (“AUX1” and “AUX2”) pins must be connected to pin 10, not pin 8, to activate them.
Sensitivity to EMI/RFI
To obtain maximum immunity to electromagnetic or radio frequency interference, make certain that the shields of
the transducer cables are connected to the “cable shield connection screw” on the rear panel of the instrument.
See “Connection of Four- or Five-wire AC/AC-LVDT”, “External Arrangement of AC powered DFI 1550 and DFI
1650” in Chapter 4 and “External Arrangement of DFI SC3004” in Chapter 4.
Non-linearity at the end of the LVDT’s mechanical range
Most LVDTs have a usable measuring range that is smaller than their mechanical range. See “Electrical Null and
Transducer Mounting” for information on establishing the LVDT’s electrical null point to insure that the LVDT will be
operated in its usable measuring range.
12.0 HIGH-LEVEL INPUT CHANNEL
12.1 Features
The High-Level Input channel provides a DC supply voltage to and accepts voltage or current signals from
amplified transducers such as pressure transducers, load cells and DC-DC LVDTs. These signals are digitized,
converted into engineering units, and placed into the track, peak and valley data values of the channels. Setup and
calibration of the channel is made manually through the SETUP menu mode. Signature Calibration is not available
with amplified transducers.