6
Sensor
Switching thresholds
Lower
Upper
Switch
100
Ω
1000
Ω
Proximity detector
1.2mA
2.1mA
Open collector
2k
Ω
10k
Ω
Magnetic pick-off
0
40mV peak
Voltage pulse low
1.0V
3.0V
Voltage pulse high
3.0V
10.0V
Switch contacts, proximity detectors and open
collector sensors require energising which is
achieved by linking two BA578E terminals together
for each input, see Fig 5.
2.2.1
Switch contact input
Any switch contact may be directly connected to
input terminals 5 & 6 or 9 &10.
The BA578E
contains a separate configurable debounce circuit
for each input to prevent false triggering. Three
levels of debounce protection are available See
section 5.5.6.
2.2.2
Open collector input
Any sensor with an open collector output such as a
opto-isolator may be directly connected to input
terminals 5 & 6 and 9 &10.
2.2.3
2-wire proximity detector input
Most NAMUR 2-wire proximity detectors may be
connected to a BA578E input, providing the
minimum operating voltage of the proximity detector
is less than 7.5V. The BA578E contains a separate
configurable debounce circuit for each input to
prevent false triggering. Three levels of debounce
protection are available See section 5.5.6.
2.2.4
Magnetic pick-off input
CoiL
in the input configuration menu is a low level
voltage pulse input intended for use with a magnetic
pick-off sensor.
The BA578E contains a separate
configurable debounce circuit for each input to
prevent false triggering. Three levels of debounce
protection are available See section 5.5.6.
2.2.5
Voltage pulse input
Two voltage pulse input ranges are independently
selectable for each input in the BA578E Timer
configuration menu,
VoLt5 L
and
VoLt5 H
allowing
almost any sensor with a voltage output to be used:
The BA578E contains a separate configurable
debounce circuit for each input to prevent false
triggering. Three levels of debounce protection are
available See section 5.5.6.
2.3
Remote reset
Connecting the external reset terminals RS1 and
RS2 together will reset the BA578E when configured
as a Timer and synchronise the displayed time to a
preset time when configured as a Clock.
Note:
When used as a Timer the BA578E may also
be reset from the display mode by operating the
&
and
*
push buttons simultaneously for more than
two seconds. See 5.5.20
2.4 Status output
All BA578E instruments have an opto-isolated open
collector output which can be configured to indicate
the status of the instrument, or to perform simple
control functions.
The output has the following
electrical parameters:
Ron
=
60
Ω
+ 3V
Roff
=
1M
Ω
Imax
=
10mA
The status output is a passive circuit i.e. un-powered
open collector, but it is totally isolated from all other
circuits. Terminals P1 and P2 may be connected to
another instrument that can accept an open collector
input.
Fig 2 shows how the status output may be used to
produce a voltage output..
The positive terminal of
the status output P1 is connected to the instrument’s
positive supply terminal 1. When the status open
collector output is activated, the voltage on terminal
P2 rises to the supply voltage less 3V and a current
flows through the resistor R1.
This current is
defined by R1 which should be chosen to limit the
current to less than 10mA. For a 24V supply R1
should be greater than 2,200
Ω
.
Fig 2 Generating a voltage status output
