Hello All, I have a CTR-502 counter module which I understand is a sourcing counter module and therefore the external input has to be a sinking source. I am testing the counter with a function generator. How do I turn a sourcing output to a sinking output? Directly connecting the function generator to the counter module does not register any counts (testing it with MAX).
Unless your function generator has a switch on it that allows it to switch between sourcing and sinking outputs, you are going to require additional hardware to meet your end goal. There are two options that could solve your problem. The first is the RLY-423 module. The other is the CTR-500 module.
Since you need additional hardware to accomplish this goal, you might want to consider purchasing the CTR-500 since it is designed with sinking inputs.
You can not directly turn a sourcing output into a sinking output, however, you can adapt two sinking or two sourcing outputs to work with each through the use of pull-up or pull down resistors. In order to connect the [c]FP-CTR-502 (sourcing) with a function generator (sourcing), you will need to place a pull-down resistor between the two. Specifically, you connect the In[x] terminal of the [c]FP-CTR-502 module to the Output of the function generator. In addition, you place a resistor between In[x] and Com of the [c]FP-CTR-502 module. The resistor size will vary based upon the voltage levels in use.
The function generator should be set to provide a unipolar output (e.g. 0 V ON, 10 V OFF, not -5 V ON, 5 V OFF) that is comparable in value to the power supply wired to the V & C terminals of the [c]FP-CTR-502. If you have wired a 12 V supply to the [c]FP-CTR-502, you should set the voltage of the function generator to 0 to 12 V. The ON voltage must be more than ~3 V less than the supply voltage (see [c]FP-CTR-502 Operating Instructions for exact specs). The OFF voltage must be within ~1 V of the power supply voltage. When using a sinking input device, the polarity is reversed (0 V ON).
It is not possible to disconnect the [c]FP-CTR-502 voltage source. If a power supply is not wired to the V & C terminals of the [c]FP-CTR-502, the isolated I/O circuitry will not have power and the modules I/O will not work.
With that said, as long as the voltage level of the power supply wired to the [c]FP-CTR-502 and the voltage level of the other sourcing device are similar (e.g. both are 12 V), it should not be necessary to disconnect the supply.