I'm not understanding a wiring diagram

I'm connecting a pulse producing flow meter to a Pro-Face PLC. The turbine flow meter is a Sponsler IT400-DC-TRL-X and it uses a Sponsler IT400 Totalizer which supplies my pulse signals to the PLC.
What's happening is while the water is flowing through the meter, I get pulses and the display on the PLC is fine/correct, but when the water stops flowing, I continue to get pulses to the PLC and my counter display continues to count.
I'm thinking I need some type of resistor to draw down the voltage (24vdc) when the meter is idle.
I'm going to attach the link for the manual for the totalizer. If you would note on page: 4 the wiring schematics shows that my pulses are coming out of TB4 terminals 1&2 and going to my external counter, (which would be my PLC high speed counter module). Now on the Pulse Out + wire, they show a 1K resistor going somewhere. Is this what I use to draw down the signal? And if so, where does the other end connect to?
http://sponsler.com/manuals/MN-IT400-R2c.pdf

The -Vs is the negative power used by your HS Counting module. It attaches to Terminal 2 as well as any appropriate terminal on the HS Counter module. Terminal 1 wires to your count terminal on the HS Counter module. Wire the resistor between this count signal and the positive voltage used by the HS Counter module (+Vs).

If you can provide input wiring diagrams for the PLC we can be more specific.

Thanks Bernie. The wiring for the PLC module is pretty straight forward...24vdc- goes to comm. and 24vdc+ signal goes to the input terminal. I'm going to try your explanation to see if that stops the pulses when the flow meter is idle.

Again, thanks alot,
Dave

The output of the flow meter, without the resistor, can just pull the signal low. It was probably a pretty wimpy signal with lots of noise. The pull-up resistor will help ensure a solid 24 volts when the signal is high. The stopped pulses might be high or low but they shouldn't be changing.

Depending on the internal wiring of the PLC.
The + with the resistor should go to your 24 volt supply of the PLC.
max is 24 mA. and the voltage should be around 1 volt in low and 24 in high pulse.
It is opto isolated so you only see a simple transistor in the line.

The meter is just simply switching your negative reference. The pullup resistor is required because you're mixing sourcing and sinking logic. The output of the meter is simply an open collector to your 24V common.

It was probably never really working correctly in the firstplace. More likely you were just counting noise.

24vdc- goes to comm, and 24vdc+ signal goes to the input terminal.

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Warning! There are some here who believe that 24VDC- does not exist and that you should label it 0 VDC! The Voltage Police are going to be watching you! I bet that if you check your power supply terminals that they are really labeled + and 0 volts...

the voltage police are going to be watching you!

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lol

Lancie1 said:

Warning! There are some here who believe that 24VDC- does not exist and that you should label it 0 VDC! The Voltage Police are going to be watching you! I bet that if you check your power supply terminals that they are really labeled + and 0 volts...

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You're absolutely right Lancie...LOL. "Old habits die hard"
Dave

Lancie1 said:

Warning! There are some here who believe that 24VDC- does not exist and that you should label it 0 VDC! The Voltage Police are going to be watching you! I bet that if you check your power supply terminals that they are really labeled + and 0 volts...

Click to expand...

No, no , it's "-24VDC" that will get you ticketed. "24VDC-" is frowned on, but still legal in these parts

No, no , it's "-24VDC" that will get you ticketed. "24VDC-" is frowned on, but still legal in these parts

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To me the two labeling versions mean the same thing, the negative terminal or wire of a 24 volt DC power supply. I think the misconception happens when you try to use the + or - as an indicator to perform some math and add or subtract the voltage. Originally it was just a polarity indicator, similar to there being two s_e_xes, M and F. If you substituted M and F, then 24M & 24F or M24 & F24 still tell the same story (voltage magnitude and direction) without the baggage of indicating arithmetic for the numbers.