Analog to pulses output

Hi everyone,
I am trying to accomplish the project, I have a Weidmuller RTD transmitter that I have it connected to PT100 this should scale from -18 to 100 Celsius. That then converted into 0-10v output. I am taking this 0-10v trying to convert it into frequency output using Red Lion VFC10000. I have hooked these up according to the diagram that came with these items but can't seem to get the frequency pulses that should be coming out of the Red Lion VFC10000. The pulses then get convert by the plc to output process value to the hmi. Anyone on here have work on analog input signal and converting it into pulses output before? I would love to get some help on this.

I would love to see the diagram of this system. It sounds a little like a Rube Goldberg setup.

Hi Bernie,
The manufacturer is no longer existed, I am just looking into finding something that will convert Rtd transmitter and output pulses signal for plc high speed counter. Do you have any recommendation? I am still learning or at least try to understand this process use by the manufacturer.

Why not just connect the 0-10vdc to your PLC?

Hi Micky,
Since I am not familiar with how the programing was written inside the plc and the manufacturer is no longer existed. Therefore, I can only try to find others products that will work with existing programing.

Could try this:

http://www.redlion.net/Products/DigitalandAnalog/Accessories/SignalConverters/AFCM.html

or something from here:

http://www.api-usa.com/signalconditioners_frequency.php

or this:

https://www.phoenixcontact.com/onli...id=2864082&library=usen&pcck=P-13-01-06&tab=1

Keith

Pin 2 is common ground for both input and output. Outputs are open collector. Are you using pullups? Manual I used.

mind the power supply it is only max 16 volts (or 230 AC)
the output should be connected to any input of a plc and a resistor of 10 kohm to the +24 volt of plc, also connect the gnd together.

I have to note you are using 3 converters in line giving poor accuracy however it does work.
the same you can do with a simple timer (555).

Hi shooter and happy new year
Thank you for the respond, you mention I can use a 555 timer. How could I accomplish with just the inline timer.
I just want to see how the pulses work. I am using Red Lion Control VFC10000

Hi Keith,

Happy new year, I read and connect the Red Lion VFC10000 but the plc could not see any pulses. The Red Lion manual did mention to use resistor for pull up, but not mention what size resistor to use. Shooter did mention using 10k ohm, how would this all get wire in?

Sorry about that. I didn't read your post as carefully as I should have.

I think shooter hit all the major points. You need to make sure that terminal 2 of the V/F converter is tied to your input module DC common. You are using a sinking DC input module, correct?

The size of the resistor is based on the minimum current required to turn on the input point of your input module and the maximum current the V/F converter output can handle. The Red Lion module can handle 10mA max. If you connect your resistor to 24VDC then it till need to be no lower than 2400 Ohms. This isn't exactly true but it is conservative. Keep in mind that the resistor is in line with the input resistance of the input module. So if the resistor value is too large the current flow through the input point will be too low and input won't turn on at all. That is what sets the upper resistance limit.

Connect the output of the V/F converter to the input point. Connect the resistor between 24VDC and the input point. In this configuration the input point will turn on when the V/F converter output is off. When the V/F converter output is on it will shunt current away from the input point causing the input to turn off.

Keith

Here is an alternate solution:
http://www.omega.com/pptst/DRP-8500.html

omronplc1 said:

Hi Keith,

Happy new year, I read and connect the Red Lion VFC10000 but the plc could not see any pulses. The Red Lion manual did mention to use resistor for pull up, but not mention what size resistor to use. Shooter did mention using 10k ohm, how would this all get wire in?

Click to expand...

Your output is internally connected to a transistor, that while off, looks like an infinite resistance. Turned on, it looks like a short to ground (or zero resistance). What the pullup resistor does is, well, pulls up the voltage from the output when it is in the off state to your system voltage (in this case, 24 volts). Since what you will have is a 10k resistor in series with the 1Meg (or so) of resistance (with the output off), it will have little to no effect on the circuit, making the output pretty much match what the V+ is. In this case the entire voltage drop is across the transistor.

Then, when the output triggers, we now have a 10k resistor in series with a 0 ohm resistor (or near enough for our purposes). Which puts the entire voltage drop across the resistor, leaving 0 volts for the output.

When you select a pullup resistor (and 10k should do just fine), keep in mind that you also need to make sure that the power rating of the resistor (in watts) is ample for the current that will be going across the resistor. Volts squared divided by resistance will give you the amount of power the resistor is dissipating.

So, connect a 10k ohm, 1/8 watt (or bigger, especially is your reduce the size of the resistor) from the +24 volts to the output of your Red Lion.

Now once you do this, and should you still not see any pulses, make sure that the input card that is on your PLC will support the pulse rate of the Red Lion.

That and a scope will tell you straight off if your Red Lion is actually pulsing.

Looking at the Red Lion documentation, I see that it has two different pulse rates (depending on whether you are connected to terminal 4 or 5). Make sure that you have the correct one selected.

And if I've got this straight, you are replacing the original equipment with the Red Lion. If that is the case, does the Red Lion match up pulse-rate wise with the original equipment?

Input current is typical 10 mA
power supply is 24 volt
24/10 = 2.4 kiloohm as best so make them 2.5 kiloohm (standard value
connect this resistor to B0 (input 0) and the other side to the 24 volt power supply
if you have a PA206 or 216 there is a internal power supply you can use. connect the common to B8 and to your rtd converter.
connect the output of the converter also to the input.
that should do the trick.
you must use a resistor as this will limit the current flowing thru your converter output.

and yes you drawing is good.

phil shall we continue here, as it is maybe usefull for others too.

recapitulating:
The RTD is connected to a converter giving 0-10 Volt output.
the range is from -18 to 100 ?celsius?
so the output is 0 volt at -18 and 10 volt at 100
the VFC10000 makes a pulse signal from this:
so 0 pulses when input is 0 volt(-18) and 100 Hz when input is 10 volt(+100)
the pulsetime is the important thing here.
suppose you measure 1 sec (better is 1 minute).
if you see 0 pulses the temp is -18
if you count 100 pulses the temp is 100

the output of the vfc must go to ground so you have to make a resistor of 2.5 kiloohm to the 24 for the plc. when everything is connected and you use a icebath for the sensor you should see flashing of the input at about 8 flashes per second.

Thanks everyone on here whom have helped me figure this out. Especially Shooter & Rootboy many thanks to both.