Rinstrum R427 - 11. Configuration; 11.2. Correct Loadcell Selection

Reference Manual Rev 1.13
Page 52 004R-646-113
11. Configuration
11.1. General Setup Information
Configuration and calibration can be performed entirely from the front panel, using
the digital setup facility. When Full Setup is used, all menu items are accessible
and care must be taken to ensure no accidental changes are made to calibration
and trade settings. In addition, there is also Safe Setup that provides restricted
access. This setup method ensures that only settings that are not calibration or
trade sensitive can be changed.
Full and Safe Setup can be passcode protected to prevent unauthorised or
accidental tampering.
11.2. Correct Loadcell Selection
It is important to ensure the signal strength from the connected loadcells is
sufficiently high to match the capability of the instrument, especially when
configuring a trade certified site.
The trade approved capability of the instrument is quoted as a maximum number of
divisions with a minimum signal strength per division in micro-volts.
To illustrate the process consider the following example:
Example
Four 2,500kg 2.0mV/V load cells are used in an application requiring a 5,000kg full
scale, with weight displayed in 5kg increments.
Calculating the total
number of
divisions:
Calculating the full
scale load cell
signal:
Calculating the
absolute signal
voltage:
Calculating the
signal resolution:
11.3. Filtering Techniques
There is a trade off between noise filtering and the step-response time of the
system. The step-response is defined as the time between placing a weight on the
scale and the correct stable weight reading being displayed. This does not affect
the number of readings per second that are taken. It simply defines the amount of
time that is required to determine a final weight reading.
The FILTER setting in the instrument setup shows the amount of time over which
the averaging is taken. Increasing the averaging time will result in a more stable
reading but will extend the time it takes the instrument to settle to a final reading.