I'm not an electrician or electrical engineer, so this may be a stupid question. I can not find the answer in the manual, so it may be worth asking it anyway:

How can I connect a sensor that counts pulses (flow meter) with an open collector output (5-15V depending on the power supply, 300 ohms resistor built in) to a digital counter input. As far as I understand the counter input wants a dry closure.

The pulse rate will be up to 5-8 Hz continuously. Or should I use an analog channel and read frequency? I really want to count pulses, because each pulse represent a calibrated volume.

Peter

PS I also have this question for a DT500 logger, out of scope here but I want to avoid cross-postings. Let me know if I should repeat the question there.

Good morning Peter,

You can do both but it would be simpler wiring into the digital section. Wire the digital input in exactly the same way as a dry closure, the output to the digital channel and the ground to the dataTaker ground.

You can also measure the output as a frequency but as it is so slow it will slow down the operating speed of the logger.

The DT5xx loggers will wire in the same way. (If you want to post this in the DT5xx section the please feel free)

Cheers,
Roger

Did that - does not work

If I try the same DT program with dry contacts, it counts OK at slow rates 1-2 Hz. (I tested the flowmeter/open collector circuit at about the same rate). Same with the DT500, btw.

I run the open collector circuit at 12 V. I checked with a scope, and the pulses are there; 0 volts off, 12 volts on. It just seems as the DT ignores them.

Should I do some magic with a resistor across the terminals to create a voltage drop, or something? I don't want to mess around with the logger too much when I really don't know what I'm doing

Peter

Good morning Peter,

Very strange, I tested this with a signal generator and it works on the bench here. The signal must be below 0.6 VDC for the signal to be seen as a Zero and Over 2.4 VDC for a One.

Can you please email me the specs on your flow sensor and I'll take a look at it?

Cheers,
Roger

All we have on the pulser is is this:

Opto-Electronic Pulser
Applications include all forms of high resolution testing for fine analysis of flow data. Typical uses are step-testing in distribution systems or for industrial process control. An electronic circuit processes the output for interfacing with other equipment, providing both bi-directional and uni-directional
information in multiple formats.

Electrical Data
The output stages are transistors configured as open-collectors with 300 Ohm series resistors for surge protection, with 1nF parallel
capacitors to 0V.
Maximum output pull-up voltage: 30V dc
Maximum output sink current: 25mA
Supply voltage: 4.5 to 16V dc
Typical supply current @ 5V: 350 mA

We run it off a 12V supply.

pj

Hi Peter,

Make sure that the ground of the sensor is connected to the ground of the DT800, and the DT800 is not going to sleep. Try connecting the sensor to the hardware counters, C7 and C8.

If you are still having problems, please email us the code to
support@datataker.com.au

Cheers
Anthony Ulrich