CNT
10
Wieland Electric GmbH | BA000917 | 01/2019 (Rev. B)
4
CNT
4.1
CNT description
The user interface CNT is for monitoring and processing analogue and binary signals and
for controlling (settings) of binary signals. There are 2 counter and 2 binary inputs or 4 bi-
nary inputs, 2 analogue inputs and 1 binary output available. The settings of binaries and
counter inputs by the help of firmware in which the single input and output is defined. Bi-
nary output is off by default configuration (is not switched to ground).
At expansion port CNT including in modem it is possible to use power supply manage-
ment. At permanent idleness the expansion port CNT is switch to low power supply mode
when demand current is very low (100
μ
A). Switch time to this status is program adjusta-
ble. The module wake up is possible by PORT status variation.
4.2
Input and output description
4.2.1
Analog input
On analogy input it detected current, converted to digital 12-bits value and modified by
multiplicative and additive constant. Next the value is averaged on user settings and stored
to PC memory. The basic range of input current is 0 – 20 mA at input resistance 100
Ohm
.
Equal of value is:
((12b value + addit. constant) * multiplic. constant)/1000
The sample period on analogy inputs is adjustable in range 0 ÷ 65535 seconds. At value 0
it is sampling once per second and measurement circuit is permanent switch on. At sam-
pling it is possible to set time of measurement circuit switch from 16 ms to 375 ms.
On the basis of signal change about bigger value then setting upper/lower limit is gener-
ated alarm. The alarm end is on the basis of bigger/lower signal change about set hystere-
sis than is upper/lower limit.
4.2.2
Binary input
The binary input is potential-free contact which is 8x per second sampling and sampling
time is 1/64 seconds. For binary inputs it is possible to set active level to either log. 0 or
log. 1. Choosing active level can generate an alarm.
4.2.3
Counter input
The counter inputs are meters maximal to 100 Hz. The ratio impulses on input can be max-
imal 1:10, that means the impulse width must not be lower than 1/10 signal period. At
lower width the true evaluation of the metered signal is not guaranteed. For metering of
small frequencies (about mHz) it is important to set the multiplicative constant which mul-
tiplies metering frequency (flow) because of true evaluation.
On the basis of signal change about bigger value then setting frequency upper limit is gen-
erated alarm. Alarm is possible send after time after which upper limit must be overrun.
In case that it isn't any change on input, it is possible to define time after which the value
on input will zero.
