PC3000 Complete Installation guide iss 12 - Elektro-Trading

General
PC3000 Installation
4 Channel Analogue Input Module
The module to be calibrated should be installed in the PC3000 rack and allowed at
least 30 minutes of warm up time prior to calibration. It is recommended that the
module be orientated vertically and the rack mounted flat (i.e not at an angle) if
application permits. This will minimize the potential for temperature gradients across
the module.
The module should be located away from heat sources such as thyristor units and
solid state relays. Draughts should also be avoided.
The use of copper cable is recommended for all calibrations unless otherwise stated.
Lead length should be minimized in order to reduce the effects of input bias current
flowing back into the calibration input source (Approximately 250mA); if long leads
are unavoidable, calibration accuracy may be improved by measuring the true
applied voltage at the input terminals of the input module and using this value as the
calibration reference rather than the value as set at source.
Calibration overview
The purpose of calibration is to eliminate or reduce inherent errors associated with
the modules hardware. As an example, the voltage references used for the analog/
digital converter have an initial tolerance; calibration serves to reduce or eliminate
this error such that the measurand reflects the true value more closely. Additionally
errors in calibration occur over time as electronic components age, requiring that
routine calibration is carried out at regular intervals.
It is not suggested that calibration is used as a means of correcting for errors associated
with the sensor; this type of error should be eliminated by use of the prelinearisation
scaler and offset parameters provided on the Analog_In Function Block.
The PC 3000 analog input module employs a two point calibration scheme in order
to correct for both gain and zero offset errors. The two arbitrary calibration points
may be calibrated independently and the resultant calibration data stored. However,
it is recommended that both points are calibrated during the same calibration
session.
Calibration is performed on the currently selected range and configuration e.g.
50mV linear, 0 to 5V etc. Each range/configuration has separate calibration data
associated with it. All ranges/configurations are calibrated when the module is
despatched from the factory.
Calibration data is stored in EEPROM in the input module.
A channel requiring calibration due to corrupted data or a ‘raw’ channel which has
no calibration data will declare the state No_Cal ( 4) via the Analog_In function
block parameter, Status_Info.
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