This is quite easy to do but you cannot make it run local currently because of restrictions in SmartThings. Only certain devices are eligible to run locally and only the official smart lighting automations. There are two different ways to do your timer, but one requires virtual devices ( which are not eligible to run locally) and the other requires custom code, and at the present time no custom code is allowed to run virtually. With that out-of-the-way, there are two options, other then writing a unique smart app, which you really don’t need and still won’t run locally.
you can do this by daisy-chaining virtual switches so that when switch turns on when another turns off and some of them turn themselves on for a specific period of time and then turn themselves off again. With those two concepts you can set up a daisy chain of switches that will give you exactly what you want.
And another example
I suppose for this when you could pretty it up with a nicer input screen to collect the variables for any specific run. And you could pay someone to do that. If you want to go that direction, post in the developers section of the forum:
The second way, which honestly is probably simpler although it’s going to look more complicated to begin with, is to use a community created rules engine called core. Very powerful, very sophisticated, can handle delays and iterations.
If you haven’t use custom code before first read the FAQ. But it’s pretty straightforward, you’re essentially just copying somebody else’s code and pasting it into your own account.
If after reading the FAQ that sounds like something you’d be comfortable with, you’ll find all the information you need about core in the following thread and people there will be happy to help you.
For your particular situation I’d recommend using core. It’s going to seem a little more complicated conceptually to begin with, but you’ll have a lot more options.
Reliability requirements
Oh, and all of that said, assuming this is for a Z wave or zigbee device, it may not be possible to guarantee that it will run 30 seconds each time. Some people have been successful with those kinds of cycles, but usually one minute is considered the minimum reliable period. So it depends in part on what kind of device this is.
Smartthings itself, and zwave in general, should never be used for anything which could impact health or safety. In fact there’s usually a black box warning on the user guide for a zwave device. Smartthings isn’t reliable enough and Zwave does not guarantee sequential operation. So for a pool filter pump, OK. For life-support machinery, absolutely not. In between, you have to make a judgment call, but I mention that because when you’re talking about A 30/30 second schedule, you’re often talking about something which requires more reliability and precision than SmartThings can offer.
