clsanchez77 (Customer) asked a question.
Hey all, I am trying to couple an Atlas Scientific 1/4" Flow Meter to a Productivity 1000 via the P1-02HSC Card.
The spec sheets on the flow meter are here: https://atlas-scientific.com/files/1-4_flow_datasheet.pdf
The spec sheets on the P1000 Card are here: https://cdn.automationdirect.com/static/specs/P1-02HSC.pdf
The flow meter has an operating range of 3vdc to 24 vdc and the HSC card has a range of 5vdc to 24vdc. I have tried running the system from 5 volts to 24 volts and I am not getting any luck. At 5vdc to 7.5vdc, the HSC card is operable but does not read the flow meter pulses. At voltages 12 and higher, the card reads the meter as shorted, and does not read any pulses. I don't have any power supplies between 7.5 and 12 to figure out where the low/off voltage is above the trigger point.
In seeing the off triggers for the card are 2.2vdc and 0.4mA, I exceed the 2.2vdc at 7vdc, however at 7vdc my off current is still greater than 0.4mA. I suspect this is the issue.
I can confirm the flow meters do work on an Arduino, so I can probably resolve the issue with a P1AM, I just did not want to introduce another PLC into this setup. I was really hoping to get these to work on the high speed counter card.
On a side note, I also tried these on the Click PLC, but the voltage triggers on the Click PLC are spread too far and the flow meter seems to operate on a tighter spec.
would it be possible to post a picture and or schematic of how you have it wired?
A picture would be difficult as the wiring is temporary and a bit of a mess. But I can describe it and try to draw a schematic later.
Currently, the V+ is wired to the VCC terminal (red wire) on two 1/4" flow meters and to GP3 (terminal 5) on the 02HSC card. I use the GP3 to verify power is getting to the meters and to provide me a reference for measuring voltages at the PLC card. The Pulse terminal (white wire) on the two flow meters is connected to the channel 1A and channel 2A terminals (Step 1 & Step 2 on terminals 2 & 7). The power supply V- terminal is tied to the 02HSC card common (terminal 1). The flow meter and PLC have common ground. The PLC gets a clean 24vdc source from another power supply.
From the power supply perspective, it looks like this:
V+: FM1-VCC, FM2-VCC, 02HSC-GP3 (5)
V-: 02HSC-C
From the flow meter perspective, it looks like this:
VCC: PSU V+
Pulse: 02HSC-Step1 (2), 02HSC-Step2 (7)
Ground: Common Ground
From the PLC P1-02HSC Card:
1 (COM): PSU V-
2 (1A): FM1-Pulse
3 (1B): N.C.
4 (1C): N.C.
5 (GP3): PSU V+
6 (COM): N.C.
7 (2A): FM2-Pulse
8 (2B): N.C.
9 (2C): N.C.
10 (GP4): N.C.
I was able to solve this myself. After responding to @z28z34man (Customer) , I started to draw a diagram and in that sketch, I realized I was not grounding my flow meter power supply V-. Once I grounded this, the system appears to work. At least the LEDs are flashing with the flow meter. I still need to get into the software and verify the functionality of it. I hit the rails with a multimeter prior to fixing it and I was reading V+ at +2.0 and V- at -10.0. The flow meters include a ground reference, so they were only seeing the +2 and thus not enough power to create the magnetic field for the hall effects I guess.
One odd peculiarity is that then when the flow meters are off, one rests as an open switch and the other rests as a closed switch. I am pretty sure they are supposed to rest open as the power draw in off is supposed to only be 8mA. The trigger in the PLC card for off is 0.4mA, so I am not sure if this is a defect in the meter, or a case of being indeterminate between low and high. Once I get the program up and running, I can better see what is going on. But I activate the meter, the LED does pulse, so I am pretty confident this is working.
I may try with my 5vdc power supply again, grounded this time, and see if it works.
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Edit, I switched it back to the 5vdc power supply and it works. Oddly enough, now meter one is resting open and meter two is resting closed. I am starting to think this is just the magnetized wheel stoping at the sensor due to the magnetic field. Since I am only counting pulses and not reading open or closed, the stop point does not matter.
Glad you got it going.
And you are correct, all the wheel and turbine flow meters that output pulses with a K factor that i have messed with is just a magnetic wheel and a pickup to to send the pulses no other electronics.
And here is the schematic.