Mecmesin MultiTest-x Series - Appendix 4 - Technical Details; Appendix 5 - Tutorials

Mecmesin MultiTest-x manual
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Appendix 4 – Technical Details
The state-of-art electronics built into MultiTest-x testing machines utilises a 32 bit
microprocessor delivering fast, accurate data acquisition together with automatic
control of product testing procedures.
Historically motorised tension/compression testers for quality control evaluation of
manufactured products have been based upon force gauges and test stands with
potentiometer controls (‘open loop’ control). The MultiTest-x range features both
automatic PID control and sophisticated measurements/analyses without the need for
a dedicated computer.
The digital control electronics consists of inputs for force and position measurement
plus limit switches for over-travel protection. A 24 bit (1 part in 16777216) A/D
converter provides high force resolution and accuracy (±0.25% FSD), while a high
accuracy rotary encoder measures position changes as small as 0.01mm. The control
output connects to an integral solid state motor amplifier that controls machine
movement. The PID algorithm, includes user-definable (factory preset) control
parameters, ensuring precise control of speed in both directions.
Control can be Monotonic, Dual Segment or Cyclic (see [1], [3], [3]) with the speeds
programmed into memory ahead of time and recalled whenever that test is to be run.
Monotonic control is a single speed test from beginning to end and can be either in
the pull (tensile) or push (compression) direction. On traditional product testing
machines, the control is via a potentiometer (open loop) and there is no automatic
facility for correcting the speed fall off. On the MultiTest-x, as the force increases, the
speed will not drop off, the PID control algorithm corrects automatically keeps the
speed constant, even up to the capacity of the testing machine. The test will stop
upon: specimen break, local overload, reaching a limit stop, test completion, pressing
[Stop/BK SP] button, or pressing the [Emergency Stop] button.
Dual Segment control provides a means of more complex control including a true hold
force feature, and
Cyclic control provides the means to cycle between either two load values or two
position values from to 1 – 999 times.
Appendix 5 – Tutorials
Commands available for developing test procedures. (see [1], [3], [3], [1]) and test
calculations (see [1], [3], [2], [1]) are listed in Section 1. In this section some simple