Hi,

Long time no hear (or write)! I have a relay that I want to drive from Digital Channel 1, operated by an ALARM. Voltage level on the channel switches between 3.6 and 0v (approx).

Can I connect the relay coil directly between dig Ch 1 and Gnd? I am a bit confused reading the manual.

Good afternoon Fred,

It will depend on the relay specification. Digital outputs 1 to 8 can sink up to 50 VDC 100 mA but we need to know the requirements of your relay?

dataTaker does not supply the power for your relay, it is simply the switch that turns the power on or off. You will need to have a power supply that matches the requirements of the relay and does not exceed the capability of the DT800.

Your relay will need to operate less that 50 VDC (12 VDC would be good) and a current draw of less than 100 mA or you will damage the dataTaker. If the relay exceeds these figures the use a smaller relay to switch the bigger relay.

The positive of the power supply will connect to the coil of the relay. Then connect the other side to the digital channel on the DT800. To complete the circuit connect the digital ground to the DT800 to the ground side of the power supply.

If your relay is normal open to close the contact you need to set the digital output to 0. (This turns on the power)

Cheers,
Roger

Thanks, Roger,

You have answered my question. I was a bit confused about powering the relay coil. But, as I suspected DT acts here just as a switch. I will be using a car battery ie 12 volts. So, it will be OK. Just will need to check the current.
Thanks for that!

Btw not exactly related, but in reading the manual one example of Alarm coding - page 100, "EXAMPLE- Alarm Action Processes: Switching an Actuator" gives as example with a line that uses [3DSO(W)=0].

What is that (W)??????? I haven't used the DT for a while and have problem finding the explanation!!!

Hi Fred,

The W stand for Working channel (Look under channel options, particularly destination), in other words the results are not displayed / logged /returned to the computer etc.

Cheers,
Roger