Relay logic simulation

Question

Hi all, 
 We've been asked to design a number of control / protection schemes lately which are increasing in complexity. Can anyone point us towards a simple software tool to model the relay logic we can use to sense-check the design (after a manual check of course) and highlight any faux pas before things get built? Really just to look at checking relays in series/parallel etc are doing the right thing, not a full-on circuit emulation, i.e., with these inputs changing to this state, we get these outputs live with that happening after the programmed delay and so on. 
 In an ideal world it would be able to read a design straight out of our CAD (ACE), but I suspect that's too much to ask! 
 Ta, 
 Jam

Aaron O&#39;Sullivan · Accepted Answer

Multi-sim or a free equivalent should do simple relay logic. 
 Heck I reckon even tinkercad could do that to be honest. 
 
 If you're looking for something you can demo hardware wise easily, grab an arduino and some switches, and you could code all that, their coding side is really simple.

Andy Millar · Answer

Jam said: It must exist somewhere surely? 
 Just found this - people have been making relay models for LTspice: 
 https://forum.allaboutcircuits.com/threads/ltspice-dpdt-relay-model.138453/ 
 LTspice is free and not too difficult to use, although it's really over the top for what you want (and might not have a delay element): 
 https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html 
 I use it about once every 5 years, just for home use these days as I'm not allowed to do real engineering any more in the day job , and it always takes me a while to remember how to actually get it to simulate anything. But it is really good for a free package once you get your head around it. You just need to remember that it's based on Pspice, which dates back to the days when we used DOS and had to do things the hard way! 
 
 I had a quick look earlier as I thought someone might have designed a specific relay simulator for rail signalling applications, and I found a few that had been done as student projects, but only conference / journal papers about them, sadly not something actually available - their supervisors were probably hoping someone would take an interest and give the universities money for it. Because of the gap in the market I do know of a serious one that's in development, but that's huge and complex (and very clever) and I'd imagine people will be charged a lot of money to use it - and it's very specifically dedicated to our strange world. A world where instead of NO and NC contacts we have front contacts and back contacts, and a "miniature" relay is the size (and weight) of a hardback book...

Csaba Zamolyi · Answer

There is also TINA. 
 I'm using quite an old version of it, but it definitely had (modular) relays in it and I have used it to test out ideas and designs for railway signaling systems based on relay logic. I created quite complex circuits and it hasn't failed on me (yet). There is some problem with delay simulation though, but it's scriptable and you can modify the relays to do that, but it's not going to be easy. 
 There are some spice formats that the software can eat, so it's not impossible to find a good relay simulation and put it in, although I haven't tried that yet.

Relay logic simulation

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