Cooper Instruments & Systems DFI 1650 Multi-Channel Digital Force Indicator - Manual (Page 9)

CF 66 3 Rev. C 2/05
• Strain-gage sensors, such as un-amplified pressure transducers and load cells
• Sensors with voltage outputs, such as transducers with the Option 2a, 2b, 2c, or 2t internal amplifier.
• Sensors with current outputs, such as transducers with the Option 2j, 2k or 2n internal amplifier
• AC-AC LVDT’s (Linear Variable Displacement Transducers)
• DC-DC LVDTs
Output Channels
Output channels are hardware circuit boards with a unique channel number. They include:
• Relay Output channels, which can add additional limits to the standard four (N/A on DFI 1550)
• DAC Output channels, which provide additional voltage or current outputs.
Virtual Channels
Virtual channels are software-based devices that occupy a channel number, but not a physical slot, in an
instrument.
• Split Display Virtual channels allow the displaying of any two channel’s track, peak or valley values at the same
time.
• Mathematics Virtual channels run small programs written in an interpretive language called SensoCode. This
provides great flexibility which allow the DFI to do many jobs which otherwise requires a personal computer or
PLC.
1.4 What is Signature Calibration?
1.4.1 Overview
A small integrated circuit is located either inside the transducer, in an in-line package between the instrument and
the transducer, or in the connector of a cable. All data necessary to set up the transducer with the instrument are
stored (even linearity data), and setup is automatic when a new transducer is connected to the instrument.
The Strain-Gage Input channel of the DFI is designed to operate with Signature Calibration. It will automatically set
itself up with transducers, which contain the memory device, but can also be set up using a front-panel interactive
procedure. The Signature Calibration module can also e programmed from the instrument’s front panel.
Signature Calibration
is only available with un-amplified strain-gage transducers.
1.4.2 Benefits
The benefits are:
• The transducer’s Calibration Record is always located where it is needed most…with the transducer.
• The instrument is always set up correctly with the transducer.
• Interchanging of transducers and instruments is a quick process.
• A User Calibration Data area that can be altered by customers to fit their requirements.
• A Factory Calibration Sheet Data area, unalterable by the customer, can be copied back into the User
Calibration Data.
1.4.3 Information Stored
The following information is stored inside transducers equipped with Signature Calibration:
• Full-scale mV/V: The full-scale millivolts-per-volt (mV/V) rating of the transducer when its full load is applied’
also called “calibration factor”.
• Shunt-Cal mV/V: The millivolts-per-volt output of the transducer when the shunt calibration resistor is placed
across its –SIGNAL and –EXCITATION leads.
• Shunt Resistance: The resistance value, in Ohms, that was used to obtain the shunt-cal mV/V value above.
• Full-Scale Value: The full-scale value of the transducer, in engineering units.
• Engineering Units: The engineering units that the transducer is calibrated in (i.e. pounds, grams pascals,
inches of water, etc.)
• Serial Number: The serial number of the transducer.
• Excitation Voltage: The magnitude and type of signal used to excite the transducer.
• Linearization Points (optional): These can be used by an instrument using Shunt Calibration or Millivolt-per-
Volt Calibration to correct any non-linearity in the transducer and thus improve the accuracy of the system. An