# Measuring sensor with two PLCs

Can I measure one sensor with two PLCs? I have a PLC that's part of a machine manufacturing stuff.

Another PLC is part of a robotic arm that needs to grab the piece.

It would be intresting to be able to read a number of sensors into both PLCs.

However I end up frying the sensors.

The sensor is a photovoltaic sensor that outputs a simple '1' (24V) or '0' (0V).

• What communication protocol are you using? – Alexander von Wernherr Nov 28 '18 at 13:08
• It might be easiest to just have one PLC read the sensor and then send that reading to the other. – Hearth Nov 28 '18 at 13:09
• Just a simple sensor connected to the PLC. It only has to give '1' (24V) or '0' (0V) as an output – RubenDefour Nov 28 '18 at 13:10
• @Felthry the problem is that it's very hard to access either PLC's – RubenDefour Nov 28 '18 at 13:10
• You don't have to use a Communication Protocol (High usage) as you say, just wire a digital output from one PLC to an input on the other. – Tyler Nov 28 '18 at 16:14

• Instead of having a PLC provide power to the sensor, you can have a separate field power supply that's independent of either PLC power.current signals (eg 4-20mA loop) cannot be shared as easily?? I don't know where you got that from. A 4-20mA sensor/transmitter can drive many devices connected in series as long as you don't exceed the rated resistance and you are on a common power source. If on different power sources, you can use signal isolators. – Moses Machua Nov 30 '18 at 18:06