hello everybody, is it possible to connect 2 PLCs analog(4-20mA) inputs from a single 4-20mA source? How? Is there available amplifier for the 4-20mA source?
Hello Michey!
Have you experience it already that you connected 2 plc input from a single 4-20mA, because if we directly connect the two plcs the current would be divided into 2, so for instance the transmitter will output 10mA the 2 PLCs will receive 5mA each. for transmitter with 0-10V for example will be ok since both will receive the same voltage levels, but here we are dealing with current.
If the PLC inputs are differential, it may work - depends on the electrical isolation between the two. If the inputs are single-ended, then you can't do it.
And yes, current inputs would be wired in series, voltage inputs in parallel.
To Everybody who contributes, thank you very much!
To EKbist, Can you explain to me in plain english what you contributed? I don't understand Greek. Thanks
Hi Mickey! are you familiar with Siemens and GE PLCs? that's the two plcs im mentioning above. And the 4-20mA Transmitter im working with is a single-ended one. do i have any option not to use isolated system?
You could connect both inputs to the PLC's in series from a single current source and as previously stated above provided that the current source can handle the loading but only if the inputs are floating (not earthed or connected to a common zero potential) otherwise it will not work. The safest is probably to use a current unit which accepts one 4-20 mA input and provides two 4-20 mA outputs.
Hi Mickey! are you familiar with Siemens and GE PLCs? that's the two plcs im mentioning above. And the 4-20mA Transmitter im working with is a single-ended one. do i have any option not to use isolated system?
Sorry, no I am not. I'm an AB and Controlmicrosystems SCADAPack
guy. I think single-ended is going to be a problem for you without
some kind of isolation.