MK1 Steel router build log 1500x800x200

[driftspin]

Aha, the same style that I have also.

Inputs:
[I'll correct the 101 mistakes in the following para, below... ignore the stuff in italics - included as a reminder for the crap I typed this morning]
So, that addresses the onto-isolated inputs. However, the design of that board presents the cathode of the onto-isolator via a 1k resistor to the input pin. The associated anode is wired to the on-board +5V supply. So, shorting the input to ground will activate the otto-isolator. Similarly, having an NPN drive to the pin *should* activate the opto-isolator, however, you have to consider a couple of issues: With the NPN drive OFF, you need a pull-up (or the NPN sensor must have a pull-up). If you intend to use 24V signalling this means that, with the sensor off, and the sensor output pulled to 24V, that you're reverse-biasing the LED fragment in the opto-isolator. My board has EL817 onto-isolators, which have a typical maximum reverse voltage of 6V. Assuming that your 24V and 5V supplies have a common ground that gives you a reverse-bias of 19V across the LED, which exceeds the data sheet value substantially.

5V switching (or 6V if that's the lowest supported by the sensor) is completely do-able.Above 11V is giving you problems. There are ways around all this - let me know if you want to investigate these options.


So, that addresses the opto-isolated inputs. However, the design of that board presents the cathode of the opto-isolator via a 1k resistor to the respective input pin. The associated anode is wired to the on-board regulated 10V supply used for the PWM output (and fed from the 12-24V input). So, shorting the input to ground will activate the opto-isolator. Similarly, having an NPN drive to the pin *should* activate the opto-isolator, however, if the sensor has a pull-up (or you've added a pull-up) you have to consider a one issue: With the NPN drive OFF and with a pull-up resistor and if you intend to use 24V signalling this means that, with the sensor off, and the sensor output pulled to 24V, that you're reverse-biasing the LED fragment in the opto-isolator. My board has Liteon LTV-817B opto-isolators, which have a maximum reverse voltage of 6V. Assuming that your 24V supply for the sensor is the same as the feed into the BoB, or otherwise have a common ground that gives you a reverse-bias of 14V across the LED, which exceeds the data sheet value substantially.

This is only an issue if you have a pull-up as part of the design (or part of the sensor). If not, then it's not an issue, but be aware although you're driving the BoB at 12-24V, the actual switching is regulated to 10V. Don't inject 24V into the inputs of this board (worst case scenario: you'll fry the opto-isolator, and possibly the onboard regulator - but protect the UCx00 controller).

It also means that the inputs are dependent on the 12-24V supply, even if you don't intend to use the PWM output. The logic on the board is dependent on the 5V supply, as are the stepper motor outputs.



Outputs:
Just remember the resistor-bank that you asked about - your drive to the stepper drivers is still 5V signalling and requires no additional resistors for current limiting. You need to source a 5V supply for the BoB, as well.



The more that I look at BoBs, the more I'm inclined to design my own extension BoB boards for the UCx00 range of controllers that give complete galvanic isolation to the input circuitry.


EDIT: Since the visual inspection, I've now metered the board and I'm happy with the info above.

I'm in the same position of trying to understand the reliable interfacing to a UCx00, although my own apathy is slowing my build.

Ok Doddy,

I did some testing on my backup bob :-).

Input pins have a 1k ohm inline onboard resistor like yours.

Test 1
Put a 12vdc psu on the bob.
Input Pins read 9.3 volts vs PSU ground/ input pin ground

test 2
Put a 24vdc psu on the bob.
Input Pins read 9.3 volts vs PSU ground/ input pin ground

Input pin output +9.3 voltage vs psu + 24vdc does not give a reading on the dvm.
So there is some type of voltage regulator on the inputs circuit.


opto`s : 1024 718B
looks like this data sheet is the right one.
http://www.everlight.com/file/ProductFile/EL817.pdf

Test 3
I tested my 6-36 vdc NPN proximity switches in 24vdc and 12vdc situation
Hooked up a 4.7 k output load on black vs blue wire.
this to test inline resistance of the proximity switch by voltage divider calculation.

It looks like i have +/- 9.4k inline resistance in the output circuit of the proximity switch.

http://www.ekt2.com/pdf/14_PROXIMITY_INDUCTIVE__8BX.pdf




Do you feel i can there for not go past 12 vdc to protect the opto`s against :
24volts PSU - 9.3volts input pin voltage = 13.7 volt reverse ?




Maybe we are trying to solve a non problem, please look at line 3 and tell me what you think.



Grtz Bert.






Feature:

1. Fully support control via parallel port, such as MACH3,etc.

2. USB power supply and external power supply are seperate for safety.

3. External power supply input: 12-24V. Equiped with anti-reverse connection function.

4. All input signal will be isolated by optical coupler for further connection with emergency stop, tool setter, limit, ect for PC saftey.

5. One relay output port for control spindle on/off. The output interface. is P17.

6. One 0-10V analog voltage output port for control of inverter that has relative analog interface,and for control of spinle speed. The output interface is P1.

7. If all 17 interfaces are activated, drivers equipped with optical coupler can be controled and 5 axis stepper motor can be controled.

8. As PWM output, P1 can control spindle speed regulator that is equipped with optical coupler.

9. Connection with 5V input drivers that has common cathode or anode is supported.