Software to close a relay at a given time via serial port?

[Basil]

I am looking for some simple software to enable, at a given time to within a second or so, derived from the PC time, activate a relay or semiconductor switch via a true serial port. Does anyone know of anything like that please? Ideally it would be able to open the relay at a later time. Just two time based changes of state would be adequate in a 24 hour period. Thanks. OS is 7 64 bit pro.

 

[samuria]

Do you have a serial port a lot don't have them now. What cmd do you need to send a simple task may do it

 

[Basil]

Do you have a serial port a lot don't have them now. What cmd do you need to send a simple task may do it

Yes, I have one on the motherboard and a card with five more true serial ports, thanks for the thought. At a given time I need an external signal to be be sent that, at the end results in a 50 Amp mains contactor turning on a big power supply. ideally I want to turn it off again at an accurate time a few hours later.

 

[samuria]

I was trying to establish what cmd you send is it something that canbedone with mode , type copy cmds

 

[Basil]

Sorry, I see what you mean now. I have no idea what command would need to be sent, something that drove one of the serial port wire states high or low I would guess. I am not sure if they handle enough current to drive a small low current relay direct, but if not i could use a semiconductor like a FET as a switch. Thanks again.

 

[Barman58]

I used to be involved with this type of system years ago and the basic control system at that time was The programmable Logic Controller with a PC input to give visual feedback and a more sophisticated control ability. These PC systems were called SCADA, (System Control and Data Acquisition), and would allow programmable actions when Virtual switches on the PC screen were clicked Etc, but the PLC was the actual controller for the valves Motors and other actual plant.

There was a move around the turn of the century to move all of this control into the actual PC but I understand recently this has gone back to the Dual layer approach.

PC-Based Controls vs. PLC-Based Controls for Machine Automation | The Material Handling Blog

You do not state what the type of and also size of your project, if it is a small or large Industrial project then the Likes of Allen-Bradley and Siemens should be examined for options.

If this is a personal project then you should be able to purchase the required actuators and software from electrical hobbyist suppliers, ( I would have suggested Maplins but they are no more), so a trawl through ebay may be the best idea.

You can also look at the leisure remote controls for RM Cars & Boats for ideas, The higher end Model railways are a good source for PC control these days as a lot use complex PC signals/Points control How to Make a Computer Controlled Model Train Set

 

[Basil]

I have been told about this software from a fellow radio amateur here in the UK and i think it will do what I need (switch on and off a huge linear variable power supply for 60V @ 50 Amps)

http://www.g4jnt.com/DropF/simpletimer.zip

Thanks for the replies, hopefully I am now sorted

 

[Botard]

If there's a signal flows through the serial port from that timer, the relay can activated. The next signal come out seems the only thing you need to sort out how to denergize the relay or do it manually.

My first thought for software was a cook timer can be downloaded from portable app but I realized you stated serial port not through audio sensor to activate the relay.

 

[Barman58]

The major issue with a serial port is that is is designed to send an analogue waveform extreme low voltage signal or a pulsed digital signal alternative. Therefore you need to fire the signal from software running in the PC to activate a specialist relay setup to react to the specific signal.

 

[Basil]

I am intending using a 60 Amp solid state relay that should have a very low mA current draw and operates from 3V upwards, so two pins activated simultaneously which this software does, should close it reliably. 60A because we all know Chinese SSR's are grossly optimistic in their rating, plus it'll be on a decent quality large heat sink. Sound OK? Thanks.

 

[Barman58]

As long as the software is designed for this purpose and the port itself is capable to hold the voltage on the two pins for the Times involved, (assuming the relay requires a continuous voltage for activation and not a Coded pulse on/off intermittent signal, which would be better as the actual current would be much less over time), I cannot see any issues, it's just down to the Math(s)