Tecfluid DFD-2 - Manual (Page 7)

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4.3 Outputs
The output has a duty cycle of about 50%. This means that he output will be "ON" for half the
output cycle and "OFF" for the other half.
For example: If we have an output pulse every 30 seconds, then the output will be "ON"
for 15 seconds and "OFF" for 15 seconds.
1. The TTL output is made by putting a 4700O resistor as a pull-up to 5 V for the opto-isolated
transistor
2. The open collector (opto-isolated) output has the following characteristics:
Maximum voltage : 30 V DC
Maximum current : 50 mA
4.4 Pulse inputs
1. The input called "COVOL" is designed to work with an electrical contact which closes the
circuit between terminals 1 and 2 of the COVOL flowmeter. Given that this type of input is
generally slow and to avoid contact bounce this input is limited to about 200 pulses per second.
2. The pick-up input is designed to work with an inductive pick-up using a coil. The input
frequency in this case is limited to about 1000 pulses per second.
3. The TTL input has a maximum frequency of about 2000 Hz.
Other types of inputs such as NAMUR, 24 V pulse are available on order.
4.5 Norms and dimensions
The DFD-2 complies with the following norms:
Electrical safety CEI 1010-1
EMC Immunity UNE-EN 50082-1
EMC Emission UNE-EN 50081-1
In the following drawings the outside dimensions and the layout of the fastening holes for
screws are given. The layout of the fastening holes is given looking at the top of the instrument.
The weight of the instrument is approximately 300 g.