Planning - Bridgeport Interact 1 linuxCNC Retrofit

You are quite a bit beyond basics. If you have to run a grounding wire to main plane, just use a large gauge quality wire to minimize impedance and you will be ok. You are right about ground loops here, don't daisy chain grounds, run a separate one to each, or just one between two planes. Best way to picture this set up would be as a star.

I received my MESA hardware yesterday!! YEA!

I started wiring my inputs to the board. I have linuxcnc booting with a minimal configuration. I can jog each axis but of course receive a following error because I have not connected my encoders of yet. Just trying to get each thing done one at a time. I'm confused on the function of the enable signals on the 7i77. Its clear as mud in my mind as of now!

Question:

Can someone explain to me in layman terms how I could connect my Servo AMPS enable to the enable inputs on the 7i77?

My enables are connected to a 24v DC relay. I have [1] 24vdc connection to each relay that requires 24vdc to activate the relay to pass my enable signal to my amps.

[Output rating of the switches is 50 mA max at 100VDC max] reading this; can I connect my 24vdc relay input to the ENA0+ and connect my DC -(NEG) common to ENA-?

I'm being very cautious because they are polarity sensitive and I don't want to destroy my 7i77.

TB5 is the 7I77s analog drive interface connector. It has both the +-10V analog
outputs and the drive enable connections. Each drive interface uses 4 pins. TB5 is a 24
pin 3.5 MM pluggable terminal block supplied with six four pin removable screw terminal
plugs.

TB5 PIN SIGNAL DIRECTION
1 ENA0- FROM 7I77
2 ENA0+ FROM 7I77
3 GND FROM 7I77
4 AOUT0 FROM 7I77


ANALOG SERVO DRIVE INTERFACE
The 7I77 provides six channels of +-10V analog servo interface on connector TB5.
Minimum load resistance is 2K Ohms. Normally analog servo drives use differential inputs
to avoid ground loops. Suggested wiring is shielded twisted pair with7I77 AOUTN to drive
AIN+, 7I77 GNDN (adjacent to AOUTN) to drive AIN- as the twisted pair and 7I77 GNDN
connected to the shield at the 7I77 end only. The drives common or GND signal should be
connected to the 7I77 power GND with a separate wire.

SERVO ENABLE OUTPUTS
Six uncommitted OPTO coupler outputs are available for drive enable. Five of these
outputs are (ENA0 through ENA4) are switched in common while ENA5 can be
independently switched for spindle applications. The ENA outputs are floating switches so
can be used for active high and active low drive enables. Output rating of the switches is
50 mA max at 100VDC max . Note that the enable outputs are polarized and can be
damaged with reverse polarity. For active high drive enables, ENAN+ should go to the
appropriate positive power supply and ENAN- to the drive enable input. For active low
enable drives, ENAN+ should go the the drive enable and ENAN- to control power ground.

cncnoob1979 wrote: Can someone explain to me in layman terms how I could connect my Servo AMPS enable to the enable inputs on the 7i77?

My enables are connected to a 24v DC relay.

You may not need the relay. In fact you probably don't need the relay.

What is the nature of the enable terminals on the drives?

Assuming that there are two of them you can determine the voltage and polarity with a multimeter in voltage mode.

If you switch the multimeter to current mode you can use the meter to connect the terminals and measure the enable current, and also check that the effect is to enable the drive.

If voltage, current and effect all check out then you can wire to the 7i77.

Andy,

Thanks for the quick reply. However I did try that, I used my multi-meter and tried to check voltages all I received were milliamps, no real voltage coming from the 7i77. I do have field power 24v wired to pin 1 on my 7i77. Do I need more than one voltage source going to my field power?

EDIT:

Sorry I misread that. You are saying to bypass the relay and go direct to the AMPS themselves.

Ill have to check on the voltage requirement in the manual.

cncnoob1979 wrote: Thanks for the quick reply. However I did try that, I used my multi-meter and tried to check voltages all I received were milliamps, no real voltage coming from the 7i77

The 7i77 enable outputs are 100V / 50 mA _switches_ not voltage outputs.

Ill have to check on the voltage requirement in the manual.

No, I was actually suggesting that you measure the voltages and enable current at the _amplifiers_ before connecting the 7i77.

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