How to control a relay with a PC

[NeoMoses]

I need help. I'm trying to do some development on a project, and I would like to be able to energize a circuit with a PC or other device that would give me an adjustable and repeatable on/off signal. For example, I may want to turn the circuit on for 1 minute, then off for 5 minutes, or I may want to have the circuit on for 45 minutes then off for 30 minutes, depending on the circumstances.

The on/off will be controlled with a relay. That part I'm comfortable with. What I'm not comfortable with is how to control a PC port from windows to send the on/off signal. I don't care if I use a serial, parallel, or USB port.

Are there any readily available programs to send a signal like this? Or am I gonna have to find someone who is comfortable with C or C++ to help me with this? Any help would be much appreciated.

I'm not dead-set on using a PC to control this, so if there is another method of making a timer that has the needed flexibility, I am all ears.

[wms]

NeoMoses,

How about a cheap Plc, (programable logic controler)?

That's what they are made for. To turn things on and off and time things or to sense presure or voltages, current ect....

I don't know tons about them, but maybe someone here does.

I also have a friend that works with this stuff for a living.
I could ask if need be.

Here's a quick link:http://www.thomasregister.com//Catal...1&uuid=TRGuest

Sorry this link doesn't get you all the way to the plc's. So you'll have to navigate to them> products>plc.
Then look at the Nano series. They have starter packages.

[bunalmis]

I send simple hardware and software.

Hardware and software use max 8 relay.
System uses PC parallel port.
I wrote for dos but not problem for Win 98.



unsigned port=0x378;
unsigned char rly0,rly1,rly2,rly3,rly4,rly5,rly6,rly7;

void on_off()
{
unsigned char dat;

dat=rly0;
dat=dat|(rly1<<1);
dat=dat|(rly2<<2);
dat=dat|(rly3<<3);
dat=dat|(rly4<<4);
dat=dat|(rly5<<5);
dat=dat|(rly6<<6);
dat=dat|(rly7<<7);
// printf("%02X ",dat);
outportb(port,dat);
}


void main()
{

rly0=0;rly1=0;rly2=0;rly3=0;
rly4=0;rly5=0;rly6=0;rly7=0; on_off();

// rly0 on 1 sec
// rly1 on 1 sec
// rly0 and rly1 off 5 sec (relay0 2 sec on, 5 sec off)
// loop again (relay1 1 sec on, 5 sec off)



while(rly0==rly0)
{
rly0=1;on_off();delay(1000);
rly1=1;on_off();delay(1000);
rly0=0;rly1=0;on_off();delay(5000);
}


}

[abasir]

NeoMoses,

A trivial VisualBasic code could achieve what you want (unless you timing is very critical, i.e., milliseconds accuracy).

For such things, I normally use a PIC (www.microchip.com) microcontroller (programming required). In most cases, it just need a chip and some transistors (& resistors, caps) and switches. Accuracy to microseconds and fully repeatable.

I could offer some help on both methods. I do need to know your 'circumstances' before suggesting a solution.

Regards

[ToyMaker]

NeoMoses:
for a relatively cheap (<USD100) highly portable (it's smaller than a credit card) solution look into the BASIC Stamp controller. It has to be programmed but you could learn everything you need in a couple of hours. The manual is free online at http://www.parallaxinc.com in .pdf format.

robotic regards,

Tom

p.s. I have no connection with Parallax, just a satisfied customer. I have purchased several hundred of their units over the years and only had one DOA, which they replaced over-nite free of charge.

[NeoMoses]

I think I'm gonna go with this. It's a kit that I get to put together, and it's got some data acquisition channels along with it!