[mxtras]

I have been reading for the last few days, searching for this info and I am a tad confused and just need some re-assurance here...I am not a electronics wizard so please be gentle...

Three basic questions:

1)Power for the breakout board - can I power the breakout board from a seperate 5VDC power supply instead of the PC power supply? From what I have read and understand the answer is yes - no problem. Is this right?

2)Power for pin Gecko 212, pin #10? - can this come from this seperate supply also or does it have to be from the same supply that powers the parallel port, meaning the power supply inside the PC? I seem to recall reading that the Gecko's 5V supply (pin 10) must be the same as the parallel port but if it's going through the bob then that makes no sense to me since the bob is isolated. What's the deal here?

3)E-stop controls? On the Gecko 212 - can pin 7 be used for disable like it can be on the 201? What is the best way to provide an E-stop circuit? I have been planning to kill the power to the drives (4 of them) but it ends up being a fairly sizable relay and I am not sure if this is the way to go anyway. I am running the motors on 48VDC, 5A per drive (peak). How should I do the E-stop circuit?

I am using Gecko 212 drives and a bob, a SSR board and a spindle speed controller - all from cnc4pc.

Thanks, guys!

:wave:

Scott

[CJL5585]

Scott,

The wiring of the 5 Volts DC to the Gecko's and the breakout board is really simple. Just wire per the following.

BOB explanation:

The breakout board pinouts are just an extension of the parallel printer port pins brought out to terminals. The pinout numbers are the same.

Pin #'s 18 thru 25 are the ground (common) side for the data pins 2 thru 17.

So, first step is to connect pins 18 thru 25 togather for a common connection. This connection is built in on some breakout boards. (CNC4PC)

Second step is to get a wallwart 5 VDC plug-in supply. (Plugs into a wall receptable). Determine the + and - wires. Connect the (-) common power supply wire to make a connection to the wires on pins 18 thru 25.

Step 3 is to connect a seperate wire from the +5 Volt side of the wallwart to each of the Gecko drives on Pin #10.

This is the extent of the 5 Volt wiring for the Gecko's.

Hope this is simple enough for you to be able to wire it up.

Jerry

[CJL5585]

3)E-stop controls? On the Gecko 212 - can pin 7 be used for disable like it can be on the 201? What is the best way to provide an E-stop circuit? I have been planning to kill the power to the drives (4 of them) but it ends up being a fairly sizable relay and I am not sure if this is the way to go anyway. I am running the motors on 48VDC, 5A per drive (peak). How should I do the E-stop circuit?

I am using Gecko 212 drives and a bob, a SSR board and a spindle speed controller - all from cnc4pc.

Thanks, guys!

:wave:

Scott

E-Stop circuit wiring:
Get a regular e-stop pushbutton and run your 48 Volts DC thru the switch. An e-stop Push Button is a normally closed switch, and when activated, opens the circuit. This will stop all Axis Movement and is wired fail safe which means if the circuit fails (opens) the stop circuit is active and safe.

This is the industry standard tried and proven method. Also, required by the National Electrical code.

Jerry

[mxtras]

Ok. External PS is OK. No problem. I have a good one in place already. Thanks for your answers, CLJ.

The E-stop, I think, is still an issue as the push buttons will be seperated - one on the control and one on the machine. I was intending to run 24VDC around the switches and then control a relay to switch the 48V for the motors. Can I use a large SSR? - - it will be a max of 20A of 48VDC = 960 watts which I think is quite a bit for a SSR?.

Would this work if mounted to a heat sink (see pic)?



Scott

[mxtras]

What if the 5VDC is removed from pin #10 from the Gecko while it is running (E-stop)?

Would this cook the Gecko?

Would this stop the motion?

Could this be used as a disable?

Scott

[CJL5585]

Scott,
Below is a link to the Crydom site and is a SSR that can handle 60 Volts DC at currents of 40 Amps DC. It can be used to switch the 48 VDC as per your ideas for the e-stop.

Per disconnecting the 5 Volts to pin #10:
Connecting or dis-connecting any wiring to the Gecko drives while voltage is applied is not recommended. It could cause serious damage to the drive module(s).

http://www.crydom.com/userResources/...rydom_D06D.pdf

Jerry

[mxtras]

Many thanks for your time, Jerry. I think (with your help) I have it licked!

Scott

[bill south]

Hey Guys;
I've seen similar threads on the 5V ps questions several times over the past year or so. But, when I bench tested my servo system with g320's, I could not get the motors to respond to mach3 when using an external 5V power supply. I had to tap the 5volts off of the control computer with an extra line. My system is soon to be finished and I'll have to rebuild the control system onto the machine. What was I missing to cause my system not to respond when using an external supply??? Unfortunately, I've since given advice here on the forum to use the computer 5V to power the gecko's when someone had a similar problem to mine. Was I giving bad advice to these folks? Hope not. Someone enlighten me!
billyjack

[CJL5585]

Hey Guys;
I've seen similar threads on the 5V ps questions several times over the past year or so. But, when I bench tested my servo system with g320's, I could not get the motors to respond to mach3 when using an external 5V power supply. I had to tap the 5volts off of the control computer with an extra line. My system is soon to be finished and I'll have to rebuild the control system onto the machine. What was I missing to cause my system not to respond when using an external supply??? Unfortunately, I've since given advice here on the forum to use the computer 5V to power the gecko's when someone had a similar problem to mine. Was I giving bad advice to these folks? Hope not. Someone enlighten me!
billyjack

If the 5 Volt common of the supply is not connected to pins 18 thru 25 on the breakout board, there is not a complete current path thru the Gecko drive electronics AND the computer parallel port and so ........ nothing happens. Also, in the Mach program you will need to select the logic to be active low. Additionally, nothing will happen if "Logic active High" is selected in Mach 3.

In my opinion engineering wise, the external 5 Volt supply is the only route to take. Otherwise, one takes the risk of blowing up or shorting out the computer power supply, the parallel port electronics, and the usb ports if power is supplied from the computer. Repair of these become very expensive.

With an external supply, the system is a complete stand alone unit. One does not have to have additional cabling which attaches to some point on the computer or laptop to get the 5 volts. The chances of blowing up some components are diminished in my opinion.

Hope this helps.
Jerry

[mxtras]

That was one of my reasons for wanting an external PS - so I could basically use the PC as just a processor - plus I had an expensive, industrial TDK power supply in my stash just begging to be used.

If I have issues with the PC, I can just replace it with another, load the software, hook up the parallel cable and I am done - no modifications to the case necessary.

Scott

[CJL5585]

Scott,

Some laptop computers have problems with furnishing the appropriate voltage logic levels when attached to breakout boards and drives.

Also, if using the laptop power supply, and it does not have the appropriate logic levels, then nothing is accomplished by trying to utilize the laptop voltage as the voltage logic levels are still not up to specifications, so operation is not really dependable.

Using an external 5 Volt supply will allow the laptop output to be as dependable as a desktop unit since the external supply is providing both the voltage and current for the external functions on the breakout board and the input to the drives and other functions. All the laptop parallel port has to do is to sink the logic current for each of the outputs.

The only thing one has to remember when using the external supply is that any program whether it is Mach software, TurboCNC, or other package is to select the output logic as being "ACTIVE LOW" in order for everything to work. This is due to the fact that current flows from power supply common to the (+) or high side of the supply.

Jerry

[mxtras]

I am not sure I really get that, but it's good to know.

Could you explain the term 'sink'? Does this mean that it completes the ground path, or? I think I am having a terminology problem.

Scott

[pastera]

The term "sink" is refering to pulling the line to a more positive potential.

In order to work correctly the inputs to the breakout board would need pullup resistors tied to the 5 volt line. This would allow the laptop to simply pull the line low and allow the pullup to raise the line to the full 5 volts.

The breakout board should have either pullup or pulldown resistors on all inputs with pullups being the best option.

Aaron

[CJL5585]

I am not sure I really get that, but it's good to know.

Could you explain the term 'sink'? Does this mean that it completes the ground path, or? I think I am having a terminology problem.

Scott

First of all, most parallel printer port circuitry (simplified) is equivalent to a pull-up resistor with one end tied to the computer 5 Volts. The other end of the resistor is connected to a NPN transistor with the emitter connected to the 5 V ground (or common).

The output going to the port is taken from the resistor/transistor (collector) connection.

The output of the computer logic goes into the input (base) of the transistor and causes a switching action.

The "Sink" I was referring to happens when the transistor is turned on and the voltage at the resistor/transistor collector is pulled low to ground. Otherwise, this voltage is at or near the +5 Volt level.


My Interpetation of the Gecko logic operation:

The +5 Volts of the external supply goes to pin #10 on the Gecko drive.
This voltage goes to the Anode of an optocoupler possibly thru a current limiting resistor. The Cathode of the optocoupler is internally connected to the input from the breakout board. (Step OR Direction Input)

(Using the Direction input as an example) When the Direction input is at a logic level of 5 Volts, the Gecko circuitry sends signals to the motor to move in one direction. When the logic level is at or near 0 Volts, the circuitry sends the motor in the opposite direction.

One can infer from this that when the logic level at the input of the Geclo direction input is at a 5 volt level that almost no current is being drawn from the computer power supply. In essence, no meaningful amount of logic current flows in the circuit. (Cathode is at +5 volts from external supply -- Anode is at +5 volts from the computer supply -- No current flow).

On the other hand, when the logic level at the direction input is at or near zero volts, the voltage flowing from the external +5 volt power supply passes thru the optocoupler Cathode (LED) out the direction input of the Gecko, thru the breakout board connections and to the transistor collector/pull-up resistor junction, thru the transistor to the ground side (Pins 18 thru 25 on the breakout board) and back to the 5 volt common (ground) completing the logic circuit. All meaningful logic current in the circuit is supplied by the external supply. The Current will flow in the reverse direction from the voltage.

I am sure that some may not accept this explanation, but it is meant to be a simplified version for those who partially understand how pull-up resistors and transistors work.

Hope this helps someone
Jerry

[CJL5585]

The term "sink" is refering to pulling the line to a more positive potential.



Aaron

Supplying voltage or current is called "Sourcing".

Jerry

[mxtras]

I am digesting.....

Thanks for the detail. It's humbling.

Scott

[mxtras]

Oh - I do have another quick question.

CJL had said in post #9 - "If the 5 Volt common of the supply is not connected to pins 18 thru 25 on the breakout board...."

On breakout board I am using I have continuity (0.3 ohms) between the 5VDC (source "negative" pin) and the ground pins 18-25. Do I still need to jump all these pins to common or do you think they are tied on the board? Again - this is a cnc4pc board.

Thanks very much for your help. The murkyness of this stuff is beginning to clear.

Scott

[mxtras]

Mariss was kind enough to answer a few related questions in another thread - I think it is all beginning to 'sink' in......(pun intended!)

http://www.cnczone.com/forums/showthread.php?t=18819

Scott

[CJL5585]

Oh - I do have another quick question.

CJL had said in post #9 - "If the 5 Volt common of the supply is not connected to pins 18 thru 25 on the breakout board...."

On breakout board I am using I have continuity (0.3 ohms) between the 5VDC (source "negative" pin) and the ground pins 18-25. Do I still need to jump all these pins to common or do you think they are tied on the board? Again - this is a cnc4pc board.

Thanks very much for your help. The murkyness of this stuff is beginning to clear.

Scott

Scott,
All you have to do is connect the - external supply to the source negative pin. It appears these connections are already made on your break-out board. So, no you do not have to wire these pins togather. I have not looked at a cnc4pc bob in a while.

I read the post by Mariss, and I am glad he listed the output drivers that would not work directly with the Gecko drives. However, with the configuration that I posted, one should hardly ever have a problem.

Jerry

Jerry