rsdoran
Lifetime Supporting Member
I was planning to show that this afternoon, even got a PM on the subject. There just are not enough hours in a day to get everything accomplished you would like too.
Here is another example showing a sinking plc output using a pull-up resistor with a sinking field device.
To calculate R you will need to know the current needed to activate the field device.
As I mentioned before the "logic" will be inverted, that means the field device will be energized when the PLC output is OFF.
Another thing to NOTE is that you have to be careful not to use this method for heavy loads which could be anything greater than 25ma...check your brand of plc to determine that part.
Here is another example showing a sinking plc output using a pull-up resistor with a sinking field device.
To calculate R you will need to know the current needed to activate the field device.
As I mentioned before the "logic" will be inverted, that means the field device will be energized when the PLC output is OFF.
Another thing to NOTE is that you have to be careful not to use this method for heavy loads which could be anything greater than 25ma...check your brand of plc to determine that part.