Tecfluid CP420R - Manual (Page 10)

10
9.4 General characteristics
Ingress protection: IP40
Ambient temperature range: 0ºC … +60 ºC
9.5 Input terminals
The pulse input is connected to a screw terminal block marked as Pulse.
Terminal
n. COVOL Turbine
1 Common Live
2 Live Live
9.6 Inputs characteristics
Note: The input terminals are not isolated from the 4-20 mA loop. Under no
circumstances can an electrical connection be made between the 4-20 mA loop and the
inputs. In the event of supplying various transmitters with the same power supply one
must make sure that the inputs are isolated between each other.
9.6.1 COVOL
If the Pulse input is configured for Covol (jumpers in position 2-3), a potential free contact
can be connected between terminals 1 & 2. Terminal 1 is connected to the common of the
instrument. This input has a 1 MΩ pull-up resistor connected to terminal 2 and to the 3,3 V
power supply. The input has a hysteresis with the switching points situated at about 1 V &
2,1 V. If an open collector transistor is to be used as the switching element instead of a
COVOL, then the aforementioned parameters must be taken into account.
Due to the presence of a filter to avoid the effects of contact bounce, the maximum pulse
frequency for the COVOL input is 130 Hz.
The minimum input frequency is 0.06 Hz
9.6.2 Turbine
If the Pulse input is configured for Turbine (jumpers in position 1-2), a coil of a magnetic
pick-up can be connected.
The input impedance is 1.2 KΩ. This input is protected to limit the maximun applied
voltage to the circuit. This protection consists of two diodes in parallel and two 100 Ω
resistors.
1 M
2 2
1 1
+3.3V
100
1K
100
2 2
1 3
Pick-up