Cooper Instruments & Systems DFI 1650 Multi-Channel Digital Force Indicator - Manual (Page 42)

CF 66 36 Rev. C 2/05
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”.
“APPLY 00000” on Power-up
The channel has detected that the transducer connected to the instrument is different than the one the channel was
last calibrated with. Because the CALIBRATION TYPE is set to either Shunt Calibration or mV/V Calibration, the
instrument is prompting you to apply zero load in order to auto-calibrate to this new transducer.
Do one of the following, depending on the situation:
• Re-connect the original transducer to the channel and re-start the instrument
• Press [ENTER] to re-calibrate the channel to this new transducer using Shunt of mV/V Calibration and accept
the presently applied load as “0”. (In situations where one can’t apply “0” load to an absolute pressure
transducer or a load cell with a pre-load, you can change the CALIBRATION DATA-ZERO-SCALE VALUE
menu item from “0” to a load that can be applied. For example, 14.7 PSIA or the known pre-load on the load
cell.
• Use the CALIBRATE menu item to perform a Known-Load Calibration with this new transducer.
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 “Un-amplified Transducer Connection to Strain-Gage Input Channel” , Figure 10-1, “External Arrangement of
AC powered DFI 1550 and DFI 1650”, Figure 4-1, and “External Arrangement of DFI SC3004”, Figure 4-5.
11.0 AC/AC-LVDT INPUT CHANNEL
11.1 Features
The AC/AC-LVDT Input channel provides an AC excitation voltage to and accepts AC signals from LVDT (Linear
Variable Differential Transformer) transducers. These signals are digitized, converted into engineering units, and
placed into the track, peak and valley data values of the channel. Setup and calibration of the channel are made
manually through the SETUP mode.
The analog-to-digital converter features adjustable digital, low-pass filtering, 12-to 18-bit resolution (depending on
the filter setting) and has several different input ranges. These many input ranges allow ±25,000 count resolution
(at the slowest filter setting) for a wide variety of LVDT outputs.
The AC/AC-LVDT Input channel is calibrated to the transducer by using known-displacement calibration.
Two rear panel control inputs can be field-configured for such functions as remote tare, disabling peak/valley
detection and clearing the peak/valley values. A standard voltage or optional current digital-to-analog output is also
provided.
To use DC/DC LVDT with a DFI instrument, use a High-Level Input channel instead of an AC/AC-LVDT Input
channel.