Advice on using Arduino to trigger lab equipment

Projects General Guidance
1

Hello,

I am looking to use an Arduino to automatically trigger a piece of lab equipment.

The equipment has a 3 pin connector on the back to allow external devices to trigger it.

The datasheet provides the following information regarding the connection:

image
image1069×336 34.8 KB

I have tested the port by using a jumper wire to bridge the trigger pin to the ground pin and it successfully triggered the piece of equipment.

Now I am looking to automate this using an Arduino to trigger the device and I am wondering what is the best approach.

Would a relay be the best bet to bridge the two pins of the connector? or would it a mosfet be a better option?

Are there any other ways to approach this? and would the use of a relay or mosfet have any limitations?

Any suggestions would be most appreciated!

2

Connect a multimeter, set to measure current, between pins 2 & 3, to trigger the equipment. How much current does the multimeter read?

Hopefully it's a tiny current, no more than a few mA.

That being the case, you may not need anything other than the Arduino output pin. For that, you must connect pin 3 to the Arduino ground.

If you would rather have more protection or isolate the Arduino ground from the equipment ground, then, yes, a relay or an opto-isolator.

3

The next step is to use your multimeter to measure the current between the 24V trigger pin and GND. Also measure the open circuit voltage between that pin and GND. It may be about 24V, in which case you cannot directly connect the pin to an Arduino output.

You will need that information to choose the best switching device, although a transistor will probably work well.

2 Likes
4

Thank you for your advice. I will measure the current tomorrow and provide an update!

Thanks!

5

My guess would be, since it is purpose built for an external trigger, an opto-coupler output between pins 2 and 3.

2 Likes
6

Which Arduino? 5 volt or 3.3 volt?

7

It would be an Arduino Giga so 3.3 volts

8

As @6v6gt said, use a 470 or 510 Ohm resistor between Arduino output pin and opto coupler input.

9

opto

1 Like
10

Best would be a voltage free set of relay contacts.

11

I would expect a Mosfet is much better than a relay. Even a BJT (aka transistor).
Being a "trigger" input it is very unlikely any real current is needed.

Next question is: What arduino are you using? If a 5V board then a mosfet is the best, if a 3.3V board then a transistor is the best

CAUTION: This will necessitate connecting the instrument ground to the Arduino ground to the ground of whatever else is connected to the Arduino. So maybe for getting started with the minimum of design effort a relay may be the way to go. It should be a small relay such as: This relay

12

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.