I have 3 E&H Promag400 flow meters that I want to connect to a single DT82I. All the inputs on the DT82I are exhausted so I am stuck with the high speed counter inputs 1C, 2C, 3C and 4C.

I have been reading through all the manuals to understand how I should wire up the flow meter frequency output terminals (24+ and 25-) to the DT82I. The flow meter output terminals are designated as passive (open collector).

Can I get assistance on the following for confirmation:

1. 24V dc + connects to 24+
2. 24V dc - connects to DGND
3. 1C connects to 25-
4. Do I need any external resistor in this circuit?
5. I see that 1C has a designation of max input terminal voltage of 10V , does that mean this 24V dc supply is beyond the capability of the DT82I?
6. On 1C, what voltage will be seen? I see that input high voltage is 2.2V and input low voltage is 0.8V. Is this signal generated by the DT82I?

Thanks,

New DataTaker user

Hi datatakeruser,

The 24+ and 25- must go to 1C and D GND as they represent the frequency signal. At the same time, the flow meter power supply will need 24V+ and 24V- which we believe have different pinouts on the sensor side.

Connecting the 24V power supply to the dataTaker side is unnecessary unless the sensor manual indicates the need.

Some sensors may need an extra resistor to boost the signal; it will depend on the wiring description. Some others can provide a frequency signal directly from the pinouts.

The frequency counter runs on a TTL signal level, with anything below 0.8V considered low and above 2.2V considered high. The signal needs to be transverse between those limits to be considered a state change, and the number of changes per second is the frequency.

Best regards,
dataTaker Expert