Direction on building a serial relay interface
Direction on building a serial relay interface
(OP)
I'm wanting to build a interface card that can control around 20 relays. I would also like to have the same amount of inputs. I'm wanting to build an interface with VB to control these relays. Also the inputs wiould be used to trigger events which vb would interperate to set the appropriate relays. I have found many different cards available however none with the amount of inputs and relays. I was thinking of building my own and was wondering if anyone had already done this and could give some advice. I'm looking at different controllers ie pic, atmel and basic stamps however it would be could if someone could point me in the right direction.
cheers
P.S I would like to the vb app to be able to query the card onstartup to determine the status of all relays.
cheers
P.S I would like to the vb app to be able to query the card onstartup to determine the status of all relays.





RE: Direction on building a serial relay interface
RE: Direction on building a serial relay interface
You can buy diecrete I/O cards using standard serial communications. For example see the following URL:
http://www.proconel.com/modmux.htm
RE: Direction on building a serial relay interface
RE: Direction on building a serial relay interface
If you'd like to have more relays than there are outputs, use multiplexing. Put some 'serial in sift register latch' chips. Then you need just three lines to control so many relays than you need (clock,data,latch).
If you use NT or Win2k then it's more complicated cause kernel doesn't allow you to write directly into LPT port, you meed device driver instead. I have seen one non commercial driver somewhere. If I find it again I'll post address.
RE: Direction on building a serial relay interface
http://www.lvr.com/parport.htm
RE: Direction on building a serial relay interface
I have a partial schematic drawn up if interested.
jdshaffer@qx.net
RE: Direction on building a serial relay interface
Her book is one of the most comprehensive, regarding the subject of serial ports. The book explains how to use Visual Basic to to form a serial interface using the MS COMM active x control that comes standard with VB 6.0