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The single-channel Model 4077 is a versatile general-purpose instrument for input of pressure, force, torque, weight, and other variables measured by DC-excited strain gage transducers.

Unlike the other 4000 Series "Standard Input Models," the 4077 provides two special analog channels for real-time capture of both positive and negative peak input values.  (ALL 4000 instruments are capable of digital peak capture, via special "MAX" and "MIN" data channels.  The validity of digitally captured peak values is necessarily limited, however, by the scan rate of the instrument's Central Processor.  This is not the case with the 4077's purely analog peak-capture capability, which yields true real-time maxima and minima, regardless of the current scan rate.)

The 4077 accepts a single input from any DC-excited load cell, pressure sensor, or other conventional 4-arm strain gage bridge, nominal 120 Ω or higher, with a full-scale range of 1.5 or 3.0 mV/V.  Optional bridge-completion circuitry is provided by the Model 10CJB-2, allowing input from a 2-wire 1/4-bridge, 3-wire 1/4 bridge, or 1/2-bridge gage configuration, as shown in Stress Analysis Using External Bridge Completion.

Advanced circuit design overcomes many of the errors traditionally afflicting the strain gage measurement process, resulting in rock-solid digital indication and noise-free analog output.

Other important 4077 features include

	selectable bridge excitation (nominal 5 or 10 VDC)
	remote sensing and regulation of bridge excitation—eliminates errors from temperature effects on cable resistance and yields consistently stable ratiometric measurement, unaffected by possible power-supply drift
	input impedance in excess of 100 megohms preserves the validity of factory calibration, prevents conversion of common-mode to normal-mode signals, and eliminates remaining errors attributable to cable resistance.  Allowable cable length has virtually no practical limits.

As with most standard 4000 Series models, both active low-pass filtering and user-selectable digital smoothing eliminate dynamic components arising from vibration, power impulses, etc., that might prevent stable digital conversion or control action (see Specifications).

The 4077's "+PEAK" channel detects and stores in capacitor memory the most positive value experienced by the input since it was last reset by an appropriate "+PEAK TRACK" command.  The "-PEAK" channel detects and stores the most negative value since the last "-PEAK TRACK" command.  Commands to control peak-capture operation may be issued via the Interface Port, by an optional Model 10P80D Extended Keyboard, or by TTL-level logic inputs received at the 4077's rear-panel I/O Connector.

Each peak value will remain in memory until reapplication of the respective "TRACK" command, or until occurrence of a subsequent more positive or more negative signal excursion (thus permitting the capture of successively higher maxima or successively lower minima).  The following diagrams show the different possible modes of real-time peak capture (and reset); see the Model 4077 Instrument Instruction Manual for complete details.

The 4077's capacitor memory is volatile, and entails inevitable decay of captured signal values.  The actual decay rate does not exceed 0.4% of full scale/second (e.g., with full scale of 20000 counts, it will not exceed 8 counts/100 msec).  The decay rate is small enough to allow essentially perfect capture and indefinite (digital) hold of signal peaks, using the special digital "MAX" and "MIN" channels, as shown in the following diagram.

For a 4077-based instrument specifically dedicated to the detection, display, and evaluation of real-time peaks in all kinds of industrial applications—and offering a special "peak trend modification"—see the Model 4K/PM-77 Peak Monitor.

Simple two-point "zero and span" calibration is provided for the 4077's input channel.  In addition, a 100-kΩ, 0.1% shunt resistor is supplied.  You can use this resistor—or one or your own—to apply an "equivalent input" for calibration purposes, when the transducer's full-scale mV/V sensitivity is accurately known.  The calibration shunt may be switched in and out for either a positive or negative up-scale reading by simple mnemonic commands issued via the Interface Port or optional Model 10P80D Extended Keyboard.

A third calibration technique for the 4077 involves application of a special MILLIVOLT/VOLT CALIBRATION (MVV) command through the Interface Port or optional keyboard when both "mV/V" sensitivity and corresponding full-scale rating of the transducer are known.

Functions Provided by the MODEL 4077 "STANDARD CONFIGURATION" (for a complete listing of the configuration, click here)

A preprogrammed tare function may be activated by front-panel button Channel Nos. 2 and 3 are "ANALOG +PEAK" and "ANALOG -PEAK" of the "live" input channel (respectively) Via front-panel buttons, you can call to display the "live" tared input; the digitally captured maximum (most positive) value of that input since last reset; the digitally captured minimum (least positive) value of that input since last reset; or the existing net difference between these digital maximum and minimum values The digital "MAX" and "MIN" functions can be reset by a front-panel button Each of the standard seven predefined limit zones of the tared input reading is tied to a specific nonlatching logic output The 4077's ±10 VDC analog output derives from the tared analog input, and is initially scaled for 1 mV of output per count

There is a special version of the Model 4077 for true, on-line Statistical Process Control (see the Model 4K/SPC-77).  For a 4077-based instrument specifically dedicated to weighing operations, see the Model 4K/WT-77 Industrial Weighing Instrument.

For typical 4077 operations, see the following applications:

	Measuring Amount of Conveyed Material (in conjunction with the Model 4040 Frequency Instrument)
	Monitoring Web Tension
	Flow Measurement Derived from Pressure Drop Across an Orifice
	Measuring Valve Opening Pressure
	Leak Testing of Hydraulic Hoses
	Closed-Loop Servo System
	Stress Analysis Using External Bridge Completion
	Automatic Sorting of Springs

4000 Series options applying to the Model 4077 include

	RS485 (network) data communications
	DC-powered (vehicle) operation

DC Strain Gage Instrument Specifications  [Top ] (Click here for 4000 Series General Specifications; see also the statement on Daytronic accuracy specifications)
Number of Inputs	One
Input Type	Conventional 4-arm strain gage bridge, nominal 120 Ω or higher NOTE: 1/4- and 1/2-bridge gage configurations can be accomplished by means of the Model 10CJB-2 Bridge Completion Card, or by equivalent external bridge completion circuitry supplied by the user.
Input Range (full-scale)	1.5 or 3.00 mV/V*
Excitation Supplied	Selectable 5 or 10 VDC, nominal; ±80 mA maximum
Normal-Mode Range	±50 mV peak operating; ±8 V without instrument damage
Common-Mode Range	±0.25 V peak operating; ±8 V without instrument damage
Common-Mode Rejection Ratio	-90 dB at DC; -120 dB at 60 Hz, 1 kHz, and 3 kHz
Input Impedance (Differential and Common-Mode)	Greater than 100 MΩ
Offset	Initial: ±0.02% of full scale Vs. Temperature: ±20 ppm/°C Vs. Time: ±10 ppm/month
Gain Accuracy	±0.02% of full scale ± 1 count LSD, typical, following calibration**
Gain Stability	Vs. Temperature: ±50 ppm/°C Vs. Time: ±20 ppm/month
Analog Peak Memory Decay Rate	Does not exceed 0.4% of full scale/second (e.g., with full scale of 20000 counts, decay rate will not exceed 8 counts/100 msec)
Analog Filtering
Filter	3-pole modified Butterworth; -3 dB at 20 Hz; -60 dB at 220 Hz
Step Response Settling Time (Full-Scale Output)	To 1% of final value: 60 ms To 0.1% of final value: 80 ms To 0.02% of final value: 125 ms
* Since channel zeroing is by digital techniques, no input balance control is provided.  The allowable input range, therefore, must include an initial unbalance (which, in commercially produced strain gage transducers, is negligible).  Other transducers may have to be externally trimmed to be used with the Model 4077, if zero unbalance exceeds 20% of full scale. ** Initial (uncalibrated) inaccuracy may be as great as ±0.05% of full scale.  Maximum error that could occur upon replacement of the Model 4077 not followed by calibration is ±0.1% of full scale.