Planning - Bridgeport Interact 1 linuxCNC Retrofit

You can drive a small relay directly with the 7I77s OPTO outputs

For example if your relay has one end connected to +24V:
+24V --> relay_coil1 --> relay_coil2 --> 7I77_ENA+ --> 7I77_ENA- --> 24V_COM

You do need a flyback diode on the relay or you will likely damage the optocoupler

Other options are:

To drive the relay with a 7I77 digital output (these are sourcing so may require re-wiring the relay)

To dispense with the relay and use the 7I77 enable outputs to directly switch the drives enable signals

What exactly does you 24v relay do? They may not be necessary. The enable outputs on the 7i77 can be thought of as analogous to a solid state relay, they are just a switch.
For example if your drive has an enable pin that has to be grounded to enable the drive, you would connect a wire from that pin to the ENA0+ on the 7i77 and connect ENA0- to a ground. If the drive enable pin has to have a voltage applied to it (say 24v) you would run a wire from a the supply (usually a pin provided on the drive) to the ENA0+ pin then connect the ENA0- pin to the enable pin on the drive. To use your relay (If it doesn't draw too much current), there is more than one way you could wire it, you could have the enable switch on the 7i77 switch the voltage supply wire to the coil or to the ground. Which ever way you choose just be sure that the current goes from the + to the - on the 7i77's switch.

For your Bridgeport enabling the servos is very simple. Just select general purpose outputs to drive the axis enable relays. You could bypass the relays and use the opto isolated drive enables on the 7i77 but it's an un-necessary complication. Enabling the drives directly with the isolated outputs it would bring high voltages to the board. That would make me a little queasy and is not necessary.

The 7i77 outputs work fine for driving small relays. Your current wiring expects the sourcing outputs that the 7i77 provides so no changes are required. The 7i77 outputs have small flyback diodes plus there are diodes on the relays so you are double protected. The 7i77 needs to have field power connected to measure anything on the output.

WOW!! You guys are awesome!

I feel like the "new girl" on a collage campus! hah

I would want to keep my existing 24v relay and I have not dove deep into the functions. I have my AMP manual listed on page 1, of this thread and looking at it, my enable depends on a 24v source. Page 14 of the manual DRV-33.pdf

I thought about just using a GPIO pin and enabling it this way. I would like to be able to use the enable pin of the 7i77 however. I'm just not wanting to fry it! As stated by csbrady, I do have fly back diodes installed on all of my relays.

Andy,
I have seen the link on machinability, but not much details were given on the wiring. 12CR,13CR,14CR are all my enable relays. You are correct that when closed they send the current to the braking resistors.

csbrady,
How did you wire yours? Did you use GPIO pins?


Todd,
To be clear, I could send 24v+ to the [7i77 EN0+], the from the [7i77 EN0-] to the relay's 24v? I'll have to look at the data sheet but I'm pretty sure my relay has around 45 `50ish ma requirement.

PCW,
Love the equipment, very nice quality and I'm very happy with the service and your customer service when I called was excellent! Thanks for the product!

Also, I have only one 24vDC power source running to the 7i77's field power block, pin 1 has +24v and pin 8 is ground. Nothing else connected to that block to power the field power.

So If im understanding the enable switch correctly, If I put +24v DC to the 7i77 enable pin [EN0+], the I can measure +24v output from the 7i77 [EN0-] pin? Its just like a switch, correct? Pass current through the switch?

Attached AMP PDF


Attached Bridgeport Interact Wiring Diagram

cncnoob1979 wrote:

So If im understanding the enable switch correctly, If I put 24v DC to the 7i77 enable pin [EN0+], the I can measure +24v output from the 7i77 [EN0-] pin? Its just like a switch, correct? Pass current through the switch?

Yup, should work, as long as you don't try to run more than 1 50mA relay / enable switch.

36.90ma to activate the relay.

attached data sheet for DC relay


So I can do one relay per axis with these? One for each enable signal per axis that is.

I wired my machine using GPIO pins and it works fine. The outputs have plenty of power to drive small relays. I didn't look at how the ENA outputs work and can't tell you if they are directional or not.