Table of Contents
Advertisement
Chapter 3 Hardware
Alternative Form Factors
As well as being available in a plastic case there are some variations of the DSCUSB that are supplied uncased. These
variants may or may not have connectors fitted. Please find connection details below.
Changing Sensitivity
The DSCUSB was designed for bridges with a nominal sensitivity of 2.5mV/V.
The absolute maximum bridge output that can be accommodated is 3mV/V. If you use bridges with a lower
sensitivity (Such as 1mV/V) you will only be using a portion of the input range so resolution suffers.
When bridges with higher than 3mV/V sensitivity must be used or those with a sensitivity less that 2mV/V that would
not yield enough resolution you will need to alter the gain of the module. This is classed as an advanced operation
and will void the module warranty.
If you want to test with an input of more than 2.5mV/V, you will have to adjust the hardware sensitivity to avoid
saturating the input. If it is less, you can correct in software alone, but increasing sensitivity will generally improve
accuracy.
To adjust the mV/V for DSC, an extra resistor 'Rg' is fitted across the pads as shown below and you may be required
to break the link track as indicated.
Identifying the 'Rg' Resistor
Identifying the Link Track
Mantracourt Electronics Limited - DSCUSB Advanced Manual
If the DSCUSB module is cased the printed circuit board (PCB)
needs to be removed from the case by undoing the two screws on
the rear.
On the PCB the Rg resistor is the pair of pads identified in this
image by the dotted outline. There is no dotted outline present on
the PCB. The pair of white arrows are present on the PCB and may
be used to identify the correct position.
The resistor is 0805 size surface mount chip.
A 0.1%, 5ppm/Deg C resistor must be used to maintain
performance.
14
Advertisement
Table of Contents
