2 webcontrol boards, 1 relay board

[MobileMe]

Is there a way to use 2 webcontrol boards to control 1 relay board? They all have there own power supplies. I have one webcontrol board that uses an 8 channel relay board that are not all used. When I try to add a second webcontrol board, it will not work. It seems to be putting voltage on to the second webcontrol board, which is preventing the use of the outputs. I got this relay board because it is not suppose to put voltage on the webcontrol board.

I can use one or the other with the relay board, but not both at the same time. Is there a way to fix the problem, or do I have to use a separate relay board for each board?

 

[apostolakisl]

What relay board are you using?  A lot of the ttl level control boards are reverse logic (they turn on when the output is off).  They do this by using a single 5v output from the cai and then sink each output individually to ground (turn output off) to turn the relay on.  If this is what you have, you'll need to scratch out the tracing on the pcb and solder in a connection to power the portion of the board that is using the second cai separately.

 

[rossw]

Is there a way to use 2 webcontrol boards to control 1 relay board? They all have there own power supplies. I have one webcontrol board that uses an 8 channel relay board that are not all used. When I try to add a second webcontrol board, it will not work. It seems to be putting voltage on to the second webcontrol board, which is preventing the use of the outputs. I got this relay board because it is not suppose to put voltage on the webcontrol board.

I can use one or the other with the relay board, but not both at the same time. Is there a way to fix the problem, or do I have to use a separate relay board for each board?

 
Not quite sure how you plan to use it... but I have one, 8-channel board split between two webcontrol boards.
WebControl board 1 uses outputs 5-8 to control LEDs and outputs 1-4 to control the relay board outputs 1-4.
WebControl board 2 uses outputs 5-8 to control other LEDs, and outputs 1-4 to control the relay baord outputs 5-8.
The only thing I needed to do was bond both webcontrol boards grounds and the relay board ground together.

 

[MobileMe]

 
Not quite sure how you plan to use it... but I have one, 8-channel board split between two webcontrol boards.
WebControl board 1 uses outputs 5-8 to control LEDs and outputs 1-4 to control the relay board outputs 1-4.
WebControl board 2 uses outputs 5-8 to control other LEDs, and outputs 1-4 to control the relay baord outputs 5-8.
The only thing I needed to do was bond both webcontrol boards grounds and the relay board ground together.

Thanks rossw, that's what I thought was the problem. Do I need to bond the relay boards ground too and not just both webcontrol boards?

 

[apostolakisl]

Again, it is important to know what relay board you are using.  If you bond two boards together and you are using the reverse logic type of relay board, you may damage your CAI board bonding them.

 

[CAI_Support]

Lou brought up a good point. It is better to not use reverse logic, rather use NC contacts than NO contacts on the relay.  However, that is not always workable.  So be careful on that.
If you are not using reverse logic, yes, bond the ground together, that might be the only way to have them work like Ross described.

 

[MobileMe]

This is the relay board I'm using...
 
http://www.ebay.com/itm/Eight-8-Relay-Module-Board-for-8051-PIC-Project-5V-/400244738836?pt=LH_DefaultDomain_0&hash=item5d30720b14
 
Thanks again Ross.  It's working great now.

 

[apostolakisl]

This is the relay board I'm using...
 
http://www.ebay.com/itm/Eight-8-Relay-Module-Board-for-8051-PIC-Project-5V-/400244738836?pt=LH_DefaultDomain_0&hash=item5d30720b14
 
Thanks again Ross.  It's working great now.

 
 
Where it says control signal state low, relay off, tells me this is not a reverse logic relay board.
 

 
Wire connection and PCB size: 
        VDD: Power supply input, 5V DC.
        GND: Power supply ground and control signal ground.
        CH_x: Control signal input, Low: relay OFF, High: relay ON.
        COM / NO / NC: (C1=COM1, C2=COM2) 
                Control signal state low, the relay OFF, COM - NO disconnected, COM - NC connected.
                Control signal stage high, the relay ON, COM - NO connected, COM - NC disconnected.