Servomex 02500003E, Quick Start Manual

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Servomex 2500 Quick Start Manual
2500 Series - Configuration and Operation 02500/003E/0 15
3.3 Analogue outputs
Each standard 2500 series analyser has 2 analogue outputs, which can now be
assigned to the measurement being made. These analogue outputs are given software
identity numbers which relate physically to the particular PCB from which they are
provided. The hardware locations and terminal strip identifiers are given in the
installation manual for each analogue output.
Each analogue output is supplied configured as current but may be set to voltage. This
selection is made as described in the installation manual.
Each analogue output has 2 sets of parameters, one for ‘Range 1’ (normal state) and
one for ‘Range 2’ (engaged when external ‘Range 2’ contact is closed, as specified in
the installation manual).
Each analogue output can be scaled across the whole measurement range of a
component (e.g 0-100% fsd corresponds to 4-20 mA), or a smaller or larger proportion
of the calibrated range. Minimum recommended analogue output range is 5% fsd,
maximum is 200% fsd (i.e. 2x over-range). Factory default is 0-100% fsd for all outputs.
NOTE
•
Above 100% fsd, linearity performance may be degraded.
•
At minimum (5% fsd) output scaling, i.e. maximum expansion of output, increased
noise may require adjustment of Time Constant (see Section 3.11).
•
Upper and lower limits of measurement for each output are entered in actual
concentration units. The lower limit can be non-zero, but cannot be higher than the
upper limit (i.e. reversed outputs not permitted).
The parameters which can be adjusted on the analogue outputs are:
i) LOWER and UPPER range of the output in the units of the measurement
(component).
ii) TRUE or LIVE zero. TRUE zero = 0 to 20 mA and LIVE zero = 4 to 20 mA.
iii) FREEZE to prevent alarms during calibration or FOLLOW so that alarms may be
activated by calibration gases.
Each of these parameters can also be independently set for range 2, if required.
LOWER and UPPER example:
2500 First Component Calibrated 0-20% CO
2
Default analogue output range :
(4-20 mA) corresponds to (0-20% CO
2
)
Minimum output range :
(4-20 mA) corresponds to (0-1% CO
2
)
Maximum output range :
(4-20 mA) corresponds to (0-40% CO
2
*)
(* = approx)