Digital to Analog I/O

I am attempting to interface a Mistras acoustic sensor to a AB Micro820.

The problem I have is the sensor logic is 3.3VDC and Micro820 is 24VDC.

I will need one signal from the PLC to the Sensor and one from Sensor to PLC, (start / stop)

One option I see is connecting the 3.3VDC discrete I/O from the sensor to the analog I/O of the Micro820 has anyone ever connected digital I/O to analog I/O or have any insight on whether it might work?

I understand a relay would be the right way, however, finding a relay that accepts 3.3VDC on the control and mountable in the box is not straight forward and I do not have a 3.3VDC source for the contact side of the relay. The enclosure I have is small so I do not have room for much more components.

Most Solid State relays will activate on 3.3 VDC.

I might of missed them then I seen 5VDC as low end for relays.

The problem still lies that for the PLC > Sensor, I do not have 3.3VDC available to run to a relay to activate the Sensor input.

Their website says that all their sensors come in different outputs 0-10v, 4-20ma, 0-5, maybe you might want to check on getting a different sensor that will work for the equipment you already have.

Just my opinion.

The various voltages you are mentioning appear to be pertaining to the Sensors analog I/O ranges (-10-10V, 0-5V, 4-20ma), my issue is with the sensor's digital I/O, I am in contact with the company and there has not been talk of a 24VDC model. The I/O of the sensor is not as flexible as a PLC or other logic devices, there is very limited things you can do with each I/O point.

I had no influence on the parts that were bought, one of the other engineers bought it all and dumped in my lap to integrate. I actually fought against getting the Micro820 but ended up with it anyways.

They do have much larger more robust systems and I am not sure of the I/O capabilities of those, however, they are overkill and much more expensive.

https://www.physicalacoustics.com/by-product/1283/

Is the sensor that we have.

^ I may be missing something but the part you linked to looks to be a device that interfaces the sensor to a PC or similar. I don't see anything about discrete I/O, nor could I find a wiring diagram on the website?

Edit: Is the I/O in that 9-pin D-Sub connector? Is there any wiring diagram or documentation you can share?

rupej said:

^ I may be missing something but the part you linked to looks to be a device that interfaces the sensor to a PC or similar. I don't see anything about discrete I/O, nor could I find a wiring diagram on the website?

Edit: Is the I/O in that 9-pin D-Sub connector? Is there any wiring diagram or documentation you can share?

Click to expand...

+1 ?

http://www.physicalacoustics.com/co...systems/1283_USB_AE_Node_Product_Bulletin.pdf

The USB does connect to a computer, it has a DB-9 connector that has 4 Analog in 1 Dig In, 2 Analog out, which can't actually be used for some reason, and one Dig Out the product bulletin on the right gives you some information the manual I could not find a downloadable manual, but it comes on a CD with the unit.

The RJ-45 connections are just links for cascading sensors

Pins 1-4 AIn Pin5 DIn Pin 6-7 AOut (cannot use) Pin 8 DOut Pin 9 GND

But regardless of pin out...the cable is already made and hooked up to the sensor unit. The issue is the 24V to 3V conflict on the Digital I/O.

I am wondering if I use the Analog I/O on the Micro820 to mimic the 3V Digital I/O on the sensor, do you think that will work? I never connected Analog to Digital I/O before and I can not find much information on it either.