18
8. ACCESSORIES
8.1 Scale card
All models have a window on the right hand side of
the display through which to view a scale card
showing the units of measurement such as
o
C,
mBar, RPM. New indicators are fitted with a scale
card showing the units of measurement specified
when the indicator was ordered, if the units are not
specified a blank scale card will be fitted. A pack
of scale cards pre-printed with common units of
measurement is available as an accessory. These
can easily be fitted on-site to the indicator without
opening the indicator enclosure or removing it from
the panel, See section 4.3 of this instruction
manual.
Custom scale cards for applications requiring less
common units of measurement are also available.
8.2 Tag information
New indicators are supplied with tag or application
information thermally printed onto the rear panel
adjacent to the terminals, legend as specified
when the indicator was ordered. This tag
information is not visible from the front of the
instrument after installation.
8.3 Alarms
CAUTION
These alarms outputs should not be used for
critical safety applications such as an
emergency shut down system.
All models can be supplied with factory fitted dual
solid state, single pole alarm outputs. Each alarm
output may be independently conditioned as a high
or low alarm with a normally open or normally
closed output in the non-alarm condition.
When the 4/20mA current powering the indicator is
removed both alarm outputs will open irrespective
of configuration. The open circuit condition should
therefore be chosen as the alarm condition when
designing an alarm system. Fig 10 illustrates the
conditions available and shows which are fail safe.
When an alarm occurs an alarm annunciator on
the indicator front panel is activated and if required
the numerical display can alternate between the
measured value and the alarm channel
identification ‘ALr1’ or ‘ALr2’.
CAUTION
The alarms are activated by the indicator’s
numerical display. Use of the Tare Function
‘tArE’ will change the numerical display, the
alarms will continue to function at the original
displayed value, but this will correspond to a
different input current.
Fig 10 Alarm outputs
Configurable functions for each alarm include
adjustable setpoint, hysteresis, alarm delay and
alarm accept.
8.3.1 Solid state output
Each alarm has a galvanically isolated single pole
solid state switch output which as shown in Fig 11.
The output is polarised and current will only flow in
one direction.
Ron
=
less than 5
Ω
+ 0.7V
Roff
=
greater than 1M
Ω
Fig 11 Equivalent circuit of each alarm output
The solid state output of each alarm may be used
to switch any dc circuit with parameters equal to or
less than:
V
=
40V
I
=
200mA
