Moran Posted December 27, 2018 Report Share Posted December 27, 2018 Hello is there any way to measure resistance with V570 PLC? is there any module i can use? i neet to check some shorts and disconnection in a cable thank Quote Link to comment Share on other sites More sharing options...
MVP 2023 Joe Tauser Posted December 27, 2018 MVP 2023 Report Share Posted December 27, 2018 The RTD module sort of measures resistance. Are you looking for an actual resistance value or for continuity in wiring? Joe T. Quote Link to comment Share on other sites More sharing options...
Moran Posted December 28, 2018 Author Report Share Posted December 28, 2018 Hi joe thanks fir your reply i need both, resistance value and continuity in wiring moran Quote Link to comment Share on other sites More sharing options...
MVP 2023 Joe Tauser Posted December 29, 2018 MVP 2023 Report Share Posted December 29, 2018 Continuity is easy - just connect +24V to one side of the wires one at a time and see if you get it on the other side. If you have a bundle to check you can switch wire feeds in with relays and make sure you only get one signal on a DI module connected to all wires. The RTD module only returns temperature from a resistance of about 25 ohms to 267 ohms. You could reverse-calculate the resistance, but I don't think this is the range you're looking for. Resistance is not so easy. Many moons ago I rolled my own ohmmeter with a DC power supply, current limiting resistors, voltage inputs on an analog module, and current sensors into another module. I was trying to measure to .01 ohm resolution on wire to make fuses and it kind of turned into a trainwreck. I learned about thermal drift of a multi-component system the hard way - I could not keep the thing calibrated. I eventually bought a really nice four-wire ohmmeter with a serial port and multiplexed it between the wires under test - the manufacturer liked it so much they asked if I would write an app note about it- https://www.tegam.com/wp-content/uploads/2015/10/AN103.pdf So this is an area I actually know a little more than the average bear about. This approach may be overkill for what you're trying to do. Can you be very specific about what you want? Joe T. 2 1 Quote Link to comment Share on other sites More sharing options...
Isakovic Posted December 29, 2018 Report Share Posted December 29, 2018 1 hour ago, Joe Tauser said: the manufacturer liked it so much they asked if I would write an app note about it- https://www.tegam.com/wp-content/uploads/2015/10/AN103.pdf That was a great story. You went for Milli-Ohms, but met great resistance. 1 Quote Link to comment Share on other sites More sharing options...
MVP 2023 Ausman Posted December 29, 2018 MVP 2023 Report Share Posted December 29, 2018 14 hours ago, Isakovic said: You went for Milli-Ohms, but met great resistance. Very cute, Isak! How is the night job coming along being a standup comic? And yes, Joe, that was a head scratcher. cheers, Aus Quote Link to comment Share on other sites More sharing options...
Cara Bereck Levy Posted January 14, 2019 Report Share Posted January 14, 2019 On 12/29/2018 at 8:27 AM, Isakovic said: That was a great story. You went for Milli-Ohms, but met great resistance. Quote Link to comment Share on other sites More sharing options...
hotwires Posted January 14, 2019 Report Share Posted January 14, 2019 An ohmmeter with an RS232 port would be the most logical approach in my mind. VOM talks ASCII to V570 via serial port then comparisons/decisions could drive outputs/actions. Quote Link to comment Share on other sites More sharing options...
Moran Posted January 14, 2019 Author Report Share Posted January 14, 2019 Hi that what i was planing to do use a multimeter with rs232. thanks for your reply Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.