How Does the [c]FP-SG-140 Determine mV/V and What Power Supply Do I Need? Hardware: Compact FieldPoint>>Analog I/O Modules>>cFP-SG-140
Problem: I am measuring strain gauges with the [c]FP-SG-140. The values it returns are in mV/V, where mV is the strain and the V is excitation voltage. I have setup the excitation voltage in Measurement and Automation Explorer (MAX) to be 5 Volts. Will the readings always be divided by 5, or is the module reading the actual excitation voltage being provided? Also, does this module require an external power supply? Solution: The [c]FP-SG-140 is reading the actual excitation voltage being applied. Therefore, when the module returns a reading of mV/V, it is not just dividing by a constant value. It is using the measured excitation voltage, which should be extremely close to the value set in MAX. This module requires no external power. The necessary excitation voltage is supplied from the backplane of the c[FP] via the controlling module. This information can be found on page 5 of the Operating Instructions for the c[FP]-SG-140, linked below. Notice that the source symbol is within the dotted line region. This indicates that the voltage comes from the module itself and that no external power is required.
By contrast, the c[FP]-DO-401 digital output module requires an external power supply. This can be seen from the diagram provided on page 4 of the c[FP] -DO-401 Operating Instructions, linked below. Notice that the source symbol is now outside of the dotted line region.
Related Links: Products and Services: NI cFP-SG-140 Products and Services: NI FP-SG-140 Products and Services: NI c[FP]-DO-401 FP-SG-140 and cFP-SG-140 Operating Instructions FP-DO-401 and cFP-DO-401 Operating Instructions Attachments:
Report Date: 08/04/2007 Last Updated: 09/19/2008 Document ID: 4C3EUL2F |
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