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pci 6509

I want to use the PCI 96 DIO to turn on relays.  The relays are rated at 8mA@24V.  I would like to know if the PCI 96 DIO can be used to sink the relay current directly.  The "top" of the relay connected to an external 24VDC supply.  The return of the external supply will be tied to the PCI DIO 96 ground. 

 

I will have protective back emf diodes across of the relays.

This direct connection would be in lieu of using drive transistors, such a 2N2222A.

 

If the above conditions are allowable, are there any suggestions for protecting the PCI 96 DIO?

 

Regards...

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Hi caljaco,

 

I think you're using the NI PCI-6509 high-current, 96 channel, 5V, DIO. If this is the case, the datasheet can be found here. The maximum sinking current for one port cannot exceed 100 mA, so I believe an 8mA current sink would be fine. 

 

You mentioned using the NI PCI-DIO-96 device. It's recommended to use the 6509 device because of the improved funcitonality. The DIO-06 would be used if your application requres the traditional/legacy NI-DAQ support. The device is going to sink a maximum current (not specified) and dicipate the rest. To protect your board, you should add a resistor to ground so that the excess current would have a path to ground. More information onteh specifications of the device can be on the product page link above in the specifications tab or in the product manual

 

Hope this helps!

Lea D.
Applications Engineering
National Instruments
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Yes, I'm using PCI 6509s.

 

From the information posted.

 

There are 12 ports, with 8 signal channels each.  Each port can support 100mA max.  My application requires 8 channels at 8mA ea which is 64mA per port.  This is OK.

 

My original question:

Is it permissible to use a 24VDC supply for the "top" of the relays whose return is connected to the PCI 6509 channel?  In the "off" condition the channel will have 24VDC connected to it via the relay.

 

From the documentation: 

"The maximum input logic high and output logic high voltages assume a Vcc supply voltage of 5 V. The absolute maximum voltage rating is -0.5 to +5.5 V"

"If you configure a DIO line as an output, do not connect the line to any external signal source, ground signal, or power supply."

 

The answer is that it isn't permissible.  I'll have to use a driver transistor as mentioned in the original post.

 

Thanks....

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@caljaco wrote:

Yes, I'm using PCI 6509s.

 

From the information posted.

 

There are 12 ports, with 8 signal channels each.  Each port can support 100mA max.  My application requires 8 channels at 8mA ea which is 64mA per port.  This is OK.

 

My original question:

Is it permissible to use a 24VDC supply for the "top" of the relays whose return is connected to the PCI 6509 channel?  In the "off" condition the channel will have 24VDC connected to it via the relay.

 

From the documentation: 

"The maximum input logic high and output logic high voltages assume a Vcc supply voltage of 5 V. The absolute maximum voltage rating is -0.5 to +5.5 V"

"If you configure a DIO line as an output, do not connect the line to any external signal source, ground signal, or power supply."

 

The answer is that it isn't permissible.  I'll have to use a driver transistor as mentioned in the original post.

 

Thanks....


That is correct! 24 V on the 6509 DO pins will let the smoke out of your device. 

 

With the 24V relays I would think about using a bank isolated DIO board similar to the PCI 6513 or 6517 (or both) the differerence is the number of DIO pins (64 and 32 sinking outputs respectively)  It is pricier in the short term but avoids having to build or purchase external relay drivers- if you can find a good one that cables nicely- and maintains the support from NI when you do blow a card (due to the bad interface you built or bought  Smiley Sad)


"Should be" isn't "Is" -Jay
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