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Actuating 24Vdc coil with MD4

Deanne 3 months ago in Master modules / MD4 updated 2 months ago 13

Trying to actuate a 24Vdc coil for a skinner valve with the MD4. I know the MD4 only has LS digital outputs so I am wondering if we would need to use incorporate a voltage divider? I plan on using a relay for that coil as well. 

Deanne- struggling to understand your comment about the need to use a voltage divider for this?

All you need to do is supply the +ve coil connection of your relay to a (fused) +24VDC supply, and the -ve of the coil to the MD4 Dout pin. Then feed another fused +24VDC through the contacts of the relay to the solenoid valve coil, the other side of which connects to 0VDC supply. You should also use a flyback diode across the relay coil for good practice and ensure the relay contacts are rated for the solenoid valve wattage and current demand.

Andry, 

Thank you. We have everything wired up, but we are not able to actuate that coil. Can this be done with the DOUT LS on the MD4?

can you post a sketch your circuit so I can see what you've done?

The MD4 Douts can drive up to 300mA each channel with max across the 4 channels of 850mA, so can easily drive a small relay coil as suggested.

Also send details of which Skinner valve you actually have (coil voltage/wattage)

Image 4301


73218BN4UN00 Skinner valve 10 watt, D100C2 coil 24VDC, using 24VDC relay with RPZF socket

like the above

your 10watt Skinner coil will draw 400mA or so, so use say a 2A quick-blow fuse (F)

We are manually able to actuate the valve now, but the DOUT-A is still not actuating the valve. Should a neg or pos be going into the DOUT? Edit: Realized DOUT needs +bat. Wondering if we need to switch out that relay since it needs to see 24VDC. Seeing an open load error on the MD4

the -ve side of your relay coil connects to the Dout pin- the +ve side of the relay coil connects to +24VDC supply.

is the application logic that switches the Dout on working correctly?  Can you view it working in Iqan Design ok?  

when the output switches 'on' its pin goes low (0V) so you get 24VDC across the relay coil and it energises. When that happens the contact closes and supplies 24VDC across the Skinner coil- it's as simple as that.

Image 4304

This is how I am actuating that valve.  The relay we are using doesn't specify polarity

Image 4305

it will work either way round, but if there's an LED fitted in the relay to show when it's energised, it won't come on if you have the coil polarity incorrect.  Standard convention is +ve to A1.

Cannot see the logic in your image, but presume the IDC is latched when the the first VDIN is pressed then released, then unlatched by pressing the second one? correct? - or show another image of all your logic for the IDC named 'coil'.

Yes, that is correct. Actuate VIN is a toggle, when pressed it sends DOUT to true. Start/Stop VIN will send DOUT to false 

not quite right

remove the toggle from 'actuate coil' VDIN and ensure the control logic in the 'activating' logic window is set to 'latching' function. 

IDC and therefore Dout will then go to 'on' when 'actuate coil' is pressed and go 'off' when 'start/stop' is pressed

you can check this is happening in iqan design and use a meter to check voltage on the dout pin 

Got it working now. Thank you very much for your help, much appreciated!