NI9205 - Use the 3.3V digital out to drive a 24V relay.

[david.ball]

I have run out of digital outputs on my cRIO hardware and found that there is a spare digital output on the NI9205 Analogue input card.

I am looking for a level shifter to allow me to drive a 24V signal into this timer relay:

http://uk.rs-online.com/web/p/time-delay-relays/7596634/ 

I have found some cheap arduino 3.3V relays, but they are a bit intermittent.

I need a device like a mosfet to take the 75uA 3.3V output from this NI9205 and change it to 24V.

I'm not having much look finiding a solution and electrical work is not my strongest area!

Has anyone used this output before?

[GerdW]

Hi David,

there are ready-to-use chips available, like this or that…

[Henrik_Volkers · Accepted solution]

Have a lok at this one:

http://www.ti.com/lit/gpn/tpl7407l

but there are more... a digikey parametric search ?

[david.ball]

Thankyou I have ordered some of these with a small empty DIN rail enclosure, I'll try to give an update after the new year if I have success

Merry Christmas

[david.ball]

Electrical stuff is not my strong point.. Any idea how i get a 24V signal from this? 

From what I understand I could connect a pullup resistor to 24V and a pull down to 0V. When the output is sinking i should get 0V and when it is not then I should get 24V?

[GerdW]

Hi david,

Electrical stuff is not my strong point.

Sure! 😄

Any idea how i get a 24V signal from this? 

From "what"?

I could connect a pullup resistor to 24V and a pull down to 0V. When the output is sinking i should get 0V and when it is not then I should get 24V?

No.

We did suggest several options. Which one did you choose?

Do you have any schematics of what you want to create/solder?

[Henrik_Volkers]

The schematic to drive a 24V relay is given in fig. 9  of the datasheet linked in the marked solution.

The output of the driver is a open collector/ open drain .  

What type of 24V signal do you need exactly?

What do you want to connect? 

No problem for a PLC input configured to read a OC signal. So tell us what you want to connect and we can tell you a solution 😄

A pull up resistor replacing the relay will give you an inverse 24V Signal. But depending on the device you connect it will be a 24V*(R_device/(R_device+R_pullup)  to 650mV Signal :).