Interface Force - Multi-axis force sensors (load cells), Pressure Sensor & Pressure Transmitters, Sensor Instrumentation, Custom Designs and Dynamic Pressure Mapping.

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Frequently Asked Questions

Here you can find a range of technical help to many of the products shown on this website as well as general information about anything relating to what we do.

What is the difference between the Interface Gold Standard Calibration software packages?

Interface offers three primary Gold Standard software packages for the calibration of load cells or test machines.

  1. Force Comparison ICS-202
  2. Machine Calibration ICS-205
  3. Dead-weight ICS-DW

All the software packages store calibration data for reference load cells, stepped load routines, 'limits' on performance criteria (where relevant) to help dramatically speed up the calibration process especially where repetitive routines are employed also at the same time helping to maintain accuracy and reduce errors.

System no.1 - Force Comparison (ICS-202)

This system requires dual channel data acquisition using either the Gold Standard PC Boards HRBSC/SCBxx or the dual channel 9840 model 9840-2xx-x. While both systems give you all the acquisition, display, manipulation, analysis and reporting functions the Gold Standard hardware has the additional option of adding a control board that provides total automation of the loading process. Regardless of how the applied force is controlled the software relies on measurements taken at stepped loading intervals, with those from a Calibration/Reference unit being compared to the Unit Under Test and then immediately performance figures are calculated and the error graph is plotted with comprehensive calculations of any parameter being available through the extremely flexible 'Crystal' report software. In-built formats are provided for a basis of ASTM-E74 and ISO-376 calibration reports. A concise operating manual will soon be available on this link.

System no. 2 - Machine Calibration (ICS-205)

While this system can be run using the dual channel hardware required by the above package it can also be operated using a single channel system more suited to the Field Calibration Engineer. This software takes the measurements from a Calibration/Reference load cell installed in the test machine and now compares the dispalyed reading of the test machine against the reference values at each stepped load interval and calculates the test machine errors at each step with tabulated results and graphical plots being offered plus immediate results can be made available in draft prior to confirmation and a signed copy. In-built formats are offered for ASTM-E4 and ISO-7500/1 calibrations. A concise operating manual will soon be available on this link.

System no.3 - Dead-weight (ICS-DW)

As above this package can be run with the dual channel hardware but only requires a single channel to measure the Unit Under Test while it is being loaded with known value reference dead-weights. Dead-weights are recognised as the most accurate way of applying known loads and the Gold Standard software will work with any number of weight-stacks to make the task of data collection a simple task of selecting the correct library files and clicking 'Start'.  A concise operating manual will soon be available on this link.

A separate note will provide comparison details for the Gold Standard Hardware.

Although reference here has been made as 'Force Calibration' the software packages can also be used for Pressure or Torque calibrations with sensors that have strain-gauged bridge outputs or high level signals of 4-20mA or +/-10V

 

 

FAQ last updated on 18 Jul 2011.

What are the Interface load cell wiring colours?

Interface USA Colors

4-Wire

Red +Excitation
Green +Signal (Tension upscale)
White -Signal
Black -Excitation
   

6-Wire

White/Red +Sense
Red +Excitation
Green +Signal (Tension upscale)
White -Signal
Black -Excitation
White/Black -Sense

 

Interface UK Colours

6-Wire

Yellow +Sense
Red +Excitation
Green +Signal (Tension upscale)
White -Signal
Black -Excitation
Blue -Sense

 

FAQ last updated on 12 Jun 2014.

How do I wire a 9840 load cell indicator connector?

Interface offers a wide selection of indicators to cover many applications and here is the basic connection details for the 9840 which is one of the most popular units for calibration grade applications.

9840 Intelligent load cell indicator - 9-way D-type load cell connector

  1. Excitation - High/Positive
  2. Sense - High/Positive
  3. Cell Output/Signal - High/Positive
  4. CellOutput/Signal - Low/Negative
  5. Sense - Low/Negative
  6. Excitation - Low/Negative
  7. Auto ID - A
  8. Auto ID - B
  9. Chassis Ground

Please contact us directly for details of the wiring for the other connectors.

Search with "What are the Interface load cell wiring colours?" for details of the most popular wiring/cable colour conventions.

FAQ last updated on 19 Jul 2011.

How do I wire the standard Interface PCCx indicator enclosure connector?

The Interface DFI05L digital load cell indicator is optionally offered with the PCCx enclosure which provides a rugged casing for protection of indicator(s) and connecting wiring espcially the mains voltage power supply leads. The rear panel provides an IEC style switched connector input and the load cell connection is via a standard D-type 15-way female connector (Male mating connector required for fitment to sensor). The wiring is as follows.

  1. Positive Excitation
  2. Positive Signal
  3. Negative Signal
  4. Negative Excitation
  5. No connection
  6. No connection
  7. Logic input - Common #07
  8. Logic input - CC.1 #08 {Tare}
  9. Positive Excitation
  10. Positive Sense
  11. Negative Sense
  12. Negative Excitation
  13. No connection
  14. Logic input - CC.2 #10 {Reset}
  15. Logic input - CC.3 #09 {Peak/Valley}

NOTE.1: The DFI05L requires 6-way sense wiring so links should be fitted between pins 9-10 & 11-12 when wiring for 4-way.

NOTE.2: To enable the front panel buttons for TARE, RESET and PEAK/VALLEY a link should be fitted between Common (pin 7) and pins 9, 15 & 14 respectively.

This information is designed to cover both the Mk1 and Mk2 style devices.

 

 

FAQ last updated on 10 Jan 2012.

What is the best excitation voltage for Interface load cells?

All Interface load cells use eight full bridge strain gauges with each leg normally being rated at 350ohms.

The preferred excitation voltage for Interface load cells is 10VDC as this guarantees the closest match to the performance achieved by Interface during calibration.  The reason for this is that the gauge factor is affected by temperature.  Heat dissipation in the gauges is coupled to the flexure through a thin layer of epoxy glue; the gauges are kept at close to the ambient temperature of the flexure. However, the higher the power dissipation in the gauges, the larger the deviation between the temperature of the gauge and that of the flexure.  For example, at 10VDC, a 350 ohm bridge dissipates 286m/w. A doubling of the voltage to 20VDC quadruples the dissipation to 1143m/w. This is a large a amount of power to have in small gauges and can cause a substantial increase in the temperature gradient between gauges and flexure.  Conversely, dropping the voltage to 5VDC decreases the dissipation to 71m/w, not a significant drop from 286m/w.

The excitation voltage has an impact on sensitivity. For example, operating at 20VDC would decrease sensitivity by approximately 0.07% from the original Interface calibration, where as operating the same load cell at 5VDC would increase sensitivity by less than 0.02%. This characteristic makes it possible to operate load cells at 5 or even 2.5VDC in order to save power. 

Some, portable data loggers will automatically switch the excitation for short period of time in order to conserve power. If the duty cycle is only 5% with 5VDC excitation, the heating effect is a tiny 3.6m/w. This could cause an increase in sensitivity of up to 0.023% from the original Interface calibration.   

Variations in excitation voltage can cause small shifts in zero balance and creep. This effect is most noticeable when excitation voltage is first turned on. The solution for this effect is to allow the load cell to stabilize by operating it with 10VDC excitation for the time required for the gauge temperature to reach equilibrium, but this can take up to 30 minutes.

  

FAQ last updated on 11 Jul 2012.

Which Interface mating connector do I need? #1

This chart details the mating connectors for the most common Interface force & torque sensor products.

Mating Connector MFG Number Mates with Application/Notes
Interface Mating Connectors
MC-001 PC06A-10-6S PC04E-10-6P 1000, 1100, 1200 Series
MC-002 PT06A-12-8S PT02E-12-8P Gold Standard Load Cells & Simulators
CN-203 PC04E-10-6P PC06A-10-6S Load Cell look-alike on cable end
CN-204 PC04E-10-6P(SR) PC06A-10-6S Load Cell look-alike on cable end
CN-206 PC06A-10-6S(SR) PC04E-10-6P Load Cells with Screw Connector
CN-207 PT06A-10-6S(SR) PT02E-10-6P Load Cells with Bayonet Connector
CN-208 MS3106A-14S-6S MS3102X-14S-6P UMC600 Indicator
CN-209 PC02E-10-6P PC06A-10-6S Box Mount looks like Load Cell screw type
CN-210 PT01A-12-8P(SR) PT06A-12-8S(SR) Gold Cell look-alike on cable end
CN-212 DE-9P DSUBMIN DE-9S 9840 Indicator Load Cell Input
CN-213 PT02A-10-6P(SR) PT06A-10-6S(SR) Load Cell Bayonet look-alike on cable end
CN-224 BINDER N/A 7-Pin Options conn. for RD6
CN-225 BINDER N/A 12-Pin for RD6, RD3, T2, T3, T4, T5, T6, T7 & T12 (>19Nm)
CN-226 BINDER N/A 6-Pin for TS11 & TS12 (>19Nm)
CN-xxx BINDER N/A 6-Pin for INF-USB/SI-USB

 

FAQ last updated on 12 Jun 2014.

What is meant by (non-)repeatability?

A peculiarity of the load cell industry is that all manufacturers seem to publicise figures for non-repeatability but these figures essentially have little or no merit. These figures could be thought of as reference values rather than actual determined values. The reasons for this are that there are no standards or definitions for a specific parameter. Although non-repeatability is generally thought to mean the variation in output for repeated loadings under identical loading and environmental conditions, there are no uniform procedures for conducting and reporting an appropriate test. There are also no means for excluding the non-repeatability of the test equipment which is often as significant as the non-repeatability of the load cell. Better measurements of the meaningful repeatability can be found in the following parameters:

  • Eccentric load sensitivity
  • Creep
  • Interpolation error
  • Temperature effect on output
  • Temperature gradient sensitivity

Interface Low Profile load cells outperform all competitive products in these key parameters

When even greater repeatability is merited , a permanently installed stud  in the live end by Interface or by the user that is locked in under tensile load, provides still greater repeatability by isolating the load cell almost completely from end effects. The pre-loaded stud increases the height of an assembly, but the overall height is still the lowest of any load cell technology available. For ultimate repeatability special versions with integral machined studs offer further improvements over the jammed studs

 

FAQ last updated on 13 May 2013.

How do I wire and setup my AMTI Gen5 amplifier for common excitation?

AMTI model Gen5 6 channel amplifier.

Some AMTI sensors use commoned excitation to reduce the cable size to fit smaller body sizes and in some instances a thinner cable helps with routing in more compact installations. The standard sensor design has 6 individual strain gauged Wheatstone bridges requiring a total of 24 cores and this can be reduced to 14 cores by commoning the excitation.

Wiring: The commoned excitation connections are made to the Fx bridge which has sufficient current to drive all 6 bridges.

Setup: It is important to set internally the excitation voltage for the remaining 5 bridges to the same value as Fx as the signal output for each bridge is calculated using the sensitivity and the excitation.

FAQ last updated on 26 Jun 2012.

How to wire a 9840 serial cable (RS-232)

The 9840 serial cable comprises normally 6-core screened cable even though only four cores are used and is fitted with a female 9-way D-type on one end and a female 15-way D-type on the other with wiring as follows.

Colour 15 Way 9 Way Function
Green 1 2 TXD
Red 2 3 RXD
White 3 6 DTR
Black 4 5 Serial GND

Although today there is a proliferation of USB connections still numerous industrial applications rely on RS-232 for a dedicated port connection to a measuring device which in this case is the Interface 9840 calibration grade digital load cell indicator. Connecting the 9840 by either serial or USB allows the instrument to be controlled from the Gold Standard data acquisition software.

FAQ last updated on 15 Aug 2012.

On a basic Interface calibration certificate what does the mV/V figure represent?

The most basic of the Interface load cell calibration certificates gives a single mV/V value but this figure has real value.

Many manufacturers only provide a Terminal value or in Interface terms RATED OUTPUT i.e. the measured signal value at full rated load, but the figure provided by Interface is the Static Error Band Output (SEB OUTPUT) which is a calculated best-fit value.

The SEB OUTPUT requires a minimum of 4 measurements at 3 points these being zero, 50% range ascending 100% range and 50% range descending.

For SSM & SM S-beam style units the provided value is that for tension measurements while the MB & MBI units are provided with compression values.

For more information contact us directly or via info@interface.uk.com

FAQ last updated on 22 Aug 2012.

What are the different force calibrations available?

We have a separate site that deals specifically with the different force calibrations, governing bodies and accreditations. To view click here or on the following image.
Click here to go to Force Calibration Guide


Alternatively call us and we will be happy to discuss your aims, look at all the options and costs so we can suggest the most suitable calibration to match your requirement.

FAQ last updated on 09 Oct 2013.

How to enable Peak/Valley on a DFI-05L load cell indicator


This is applicable to the standard DFI-05L MK2
(may vary if the MEM-08 option is installed.)
Assuming that the default conditions apply to the Logic Inputs it is necessary to link connection 7 to 9 (Common - CC.2) & 10 (Common - CC.3) to enable Peak/Valley (Max/Min) and Reset respectively.
load-cell-indicator-DFI-05L-logic-inputs.jpg

With the Calibration Lock Switch is in the locked position the unit will operate as follows.
Press once -
Displays PEAK (MAX)
Press-once
Press twice -
Displays VALLEY (MIN)

Returns to normal after
a short period
or Press a third time
Press-2
Press for 3 seconds -
RESETS values of Peak & Valley
Press 3 seconds

FAQ last updated on 01 Oct 2013.

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