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Section 7 -
Principles
7.1
Introduction
This section describes the principles used in the CCD100. It details the various settings for
the inputs and the outputs including setpoint control. It does not detail any servicing or
calibration procedures.
7.2
Analogue Inputs
The CCD100 has two analogue voltage input channels. The main input can be configured
to accept any input voltage from 0V to a full scale of up to 10V. This input is calibrated
using a straight line fit method and then can be displayed on the CCD with an applied
range. The secondary input is used to accept an external command setpoint and has a
non-configurable full scale of 10V. This input is used when the setpoint is set to slave
source.
Note for millivolt option:
The full scale is represented in mV rather than V and can be
configured to 250mV max.
The main input channel has a number of associated setup parameters:
(a)
Range
Each device attached to the CCD will be outputting a voltage that represents some
form of units and the range is used with the full scale to determine what the user
sees on the screen for any input voltage.
(b)
Full Scale Voltage
Each device attached to the CCD will have a full scale voltage which is the
maximum voltage the device should output under normal operating conditions.
Typical values are 10V, 5V and 1V. The full scale is used with the range to determine
what the user sees on the screen for any input voltage. The CCD will show the over
range error (“RANGE”) for any channel whose voltage input is more than 15% over
the full scale voltage set for that channel.
(c)
Units String
To inform the user of what units are being dealt with, each channel has an
associated units string. This is a free form text field (maximum 5 characters) that is
displayed on the right side of the Main screen.
Example
A device has a full scale voltage of 10V and a range of 100 mbar.
If the device now outputs 10V, the CCD100 display will nominally show 100 (pending input
calibration). If the device outputs 5V, the CCD100 will show 50, and so on.
7.3
Analogue Outputs
There are two analogue outputs on the CCD100, both voltage outputs. One is for setpoint
control with its own set of setup parameters (see next section) and the other is a simple
retransmission of the main input voltage and has no user setup control. Typically this
output can be used for data logging purposes or for providing an external setpoint control
to another CCD or similar instrument.
