In the measurement industry, the range is a familiar term. The choice of range should first protect the instrument from reducing its reliability or being damaged during the test; secondly, reduce the measurement error and improve the credibility of the test results. When testing, it is well known that you choose a range that is larger than and closest to the measured signal value.
For example, to test the 220VAC mains signal, there is a 300V multimeter and a 1000V multimeter. There is no doubt that you must choose a 300V multimeter.
You may know that this choice can reduce the measurement error, but do you know the principle?
This is because selecting a range that is greater than and closest to the measured signal value can reduce unnecessary full-scale error.
What is the full scale error?
In the test instrument industry, accuracy is one of the most important indicators of the instrument. Accuracy is the error range of the instrument's measured values. The error type is divided into "error proportional to the measured value" and "fixed error independent of the measured value". The accuracy index of the general instrument is the sum of the two errors. For example, the power analyzer PA6000 has a power accuracy of 0.02% reading + 0.04% of the range in the working frequency range (45 Hz to 66 Hz), as shown in Table 1. Among them, the reading error is an error proportional to the measured value, and the range error is a fixed error, that is, a full-scale error.
Table 1 PA6000 measurement accuracy
Assume that the power analyzer PA6000 is selected to test the 220VAC mains signal, and its voltage range is shown in Table 2.
Table 2 Voltage measurement range 
When testing with a 300V range,
Full scale error
0.04% range=0.04%*300=0.12V
Absolute error is
0.02% reading + 0.04% range = 0.02% * 220 + 0.04% * 300 = 0.164V
Relative error is
0.164/220*100%=0.0745%
When testing with the 1000V range,
Full scale error
0.04% range=0.04%*1000=0.4V
Absolute error
0.02% reading + 0.04% range = 0.02% * 220 + 0.04% * 1000 = 0.444V
Relative error
0.444/220*100%=0.2018%
From the above results, it can be clearly seen that by selecting the 300V range close to the measured value, the full-scale error can be reduced by 0.28V (0.4-0.12=0.28V), and the relative error can be reduced by 0.1273% (0.2018%-0.0745%=0.1273%).
Therefore, in order to reduce unnecessary full-scale error and improve test reliability, it is necessary to select a range larger than and closest to the measured signal value.
984 controllers are available in four generic hardware classes: Large, rugged, high-performance chassis mount controllers Rugged, midrange-performance slot mount controllers, which reside in a primary housing beside 800 Series I/O Modules Host-based controllers built on various industry-standard computer cards designed to reside in and execute control logic from a host computer Low-cost, easy-to-install compact controllers, for applications with less demanding environmental and performance requirements The family approach to 984 controller design allows you to make choices based on controller capacity (the number of discrete and analog/register points available for application programming, the number of I/O drops it supports), throughput (the rate at which it solves logic and updates I/O modules), and environmental hardness (the design standards its hardware implementation must meet).
A major advantage of the family approach to 984 controller design is product compatibility. Regardless of its computational capacity, performance characteristics, or hardware implementation, each 984 controller is architecturally consistent with other 984s. The 984 instruction set (the functional capabilities of the controller, part of the system firmware stored in executive PROM) comprises logic functions common to other 984s. This means that user logic created on a midrange or high-performance unit such as a 984-685 or a 984B can be relocated to a smaller controller such as a 984-145 (assuming sufficient memory in the smaller machine) and that logic created on a smaller controller is upwardly compatible to a larger unit. As your application requirements increase, it is relatively easy to upgrade your controller hardware without having to rewrite control logic. Also, training costs and learning curves can be reduced, since users familiar with one 984 model automatically have a strong understanding of others.
Modicon PC0984 Programmable Controller
Modicon PC 0984 Programmable Controller,Communication Processor,Processor Module,CPU Module
Xiamen The Anaswers Trade Co,.LTD , https://www.answersplc.com