Wiring Interposing Relays - Isolating NPN and PNP Sensors into the PLC

We will now look at wiring interposing relays to connect an NPN and PNP sensors into the PLC. Interposing relay means a device that will separate two different circuits. The isolation can be for current consumption, voltage differences, voltage references, or a combination of both current and voltage. We can use these relays to help connect our inputs and outputs to our programmable logic controller. (PLC) Voltage References When wiring NPN and PNP sensors, we cannot mix them together with the same common input point of the PLC. This is because in an NPN connection the common input point will be at 24VDC. The PNP connection will place the common input point at 0VDC. If we were to wire both of these to the same common we would create a short across our power supply. This could damage the power supply and the PLC inputs. An interposing relay can be used to keep the voltage references separate. We will look at an example of using an interposing relay to wire an NPN and PNP sensor into the PLC. More information can be obtained at our website. This includes all of the links mentioned in this video. https://accautomation.ca/wiring-interposing-relays/ 00:00 Wiring Interposing Relays - Isolating NPN and PNP Sensors into the PLC 00:21 Current Consumption – Voltage Differences - Voltage References 01:02 Wiring PNP to Input - Omron CP1H 01:55 Wiring NPN via Interposing Relay to Input - Omron CP1H same common Here are the specifications for the Omron G3R solid state relay that we will use in our example. This will be the interposing relay for our circuit. https://www.components.omron.com/components/web/pdflib.nsf/0/8BDF28823490BA4685257201007DD5B9/$file/G3R_IO_0911.pdf The PNP sensor will be a Sick IM12-04BPS-ZWB proximity sensor. Here are the specification sheets. https://www.sick.com/media/pdf/3/83/483/dataSheet_IM12-04NPS-ZWB_6012036_en.pdf http://www.winters.com.ar/pdfs/IM12-standard.pdf The NPN sensor will be an Omron E2E-X5E1. Here are the specification sheets. https://www.limasoft.cz/omron/pdf/e2e.pdf We first of all will wire the PNP sensor up to the first input of the PLC. The common point will now be at 0VDC for all the inputs that share the same common. We will use the coil of our interposing relay as the load on our NPN sensor. When the sensor switches it will now energize the coil and in turn, switches our contacts. The contacts will then be wired from the 24VDC side to the next input of the PLC. Here is some additional information on wiring PLC inputs. Wiring NPN Sensor to PLC https://youtu.be/Z09l3HKMpqs https://accautomation.ca/heres-a-quick-way-to-wire-npn-and-pnp-devices/ Wiring PNP Sensor to PLC https://youtu.be/nP33k5e_Y-k https://accautomation.ca/heres-a-quick-way-to-wire-npn-and-pnp-devices/ Wiring Contact Discrete PLC Inputs https://www.youtube.com/watch?v=xh5dE2Z09d0 https://accautomation.ca/how-plc-inputs-work/ ACC Automation https://accautomation.ca/