CNC_0034

OTHER: CNC Work Station - Controller - Servodrive Status Board

Electrics:

Definitions & Algorithms

Symbols

Schematic: See Servo Status Board on drawing 1484.dc

Board Layout: See drawing 1487.dc

Notes:

When connecting Servodrive Status Board, remove jumper wire on Geckos between ERR/RES (term.5) and ENC+ (term.7). DONE

The inputs are from the Gecko G320, terminal 5 [ERR/RES] ~ (Active HI)

The voltage on this terminal is +5VDC when the G320 is functioning normally.
The voltage on this terminal goes to 0VDC when an error has occurred. This causes PN2907 to draw current through the LED.

The output is to the Parallel Port, pin 10. ~ (active LO). The EStops and Travel Limits went to this port, but now the go to the Servodrive Status Board. Does this mean that Mach3 stops when the wire goes Lo?

The Gecko G320, terminal 5 [ERR/RES] is ANDed with the EStop output from the [EStop and Limits Board] and sent to Parallel port #10 (active LO), Does this mean that Mach3 (in the computer) stops when this wire goes LO?

From looking at the Gecko schematic, there does not appear to be a need for any additional resistors. Not for between Gecko's ERR/RES (term. 5) and the Momentary Center Off switch. Nor at the base of the transistor switch for the led.

Transistors in Lieu of Relays: The use of transistors in lieu of relays is a more elegant way to go. The board layout drawing is 1487_WITH_TRANSISTORS.dc and the scematic is on the drawing 1484.dc. However the transistors for Engage / Disengage are not wired correctly and board is not working correctly. The following are posts by fkaCarel on CNCzone re the correcting of this problem.

There are no current limiting resistors on the bases of the transistors. You combine the driving of the error leds with outputting signals. Through the load of the Led's your 1-signal will not go over 1 volt. So it won't work. You have logic on the right side, now put it also on the left side and drive the led's separately.

Carel

A transistor is an amplifier. So you need a small current on the basis to get a greater current to flow from collector to emitter. This is the current limiter, normally 4k7-10k. Then for a rigid design you have to predefine the states of the inputs. Your inputs are "floating". If the switches are open there is no determined state of "0" or "1". Use longer wires and your circuit will dance with your local radiostation. You use the middle of the totempole (the two serially connected transistors) to drive your status led transistor AND your logic (4-port NAND with inverting inputs?). The transistor loaded with the loads takes care of the fact that the voltage on this line can never reach a logical "1". The load is to heavy. I have not the faintest idea what you try to achieve with this circuit, I can only see that it does'nt work. It looks like you want the circuit to maintain a state after you toggled a switch. So put your cards on the table and let's see how we can help.

Carel

At some time in the future consider making a new board using transistors ~ when I figure out how to do it.

Components:

Engage-Disengage Switch; .MODE 42-427-1 Toggle switch, SPST (on)-off-(on), Momentary contact, 15Amps@ 145VAC

Transistors (switches): The schematic on Gecko recommends the PN2907 PNP transistor to work with the Fault LED. It appears that the board will need 12 only PN2907 PNP general purpose amplifier switches and 6 only comperable NPN general purpose amplifier switches

LEDs: 6 red. In series with 220 ohm resistors.

Inverter [NOT gate]: The SL74LS06 has open-collector output. It therefore needs a pull up resistor or a load of some kind on the collector (Output) in order to register an output. I put a 4.7K resistor between the output and the %VDC and all looks well. See the hard copy notes in the binder tab Servo Board for more information. Open Collector means you got to tie it to some pull-up resistor network....if the output is a TTL output then you don't need the pullups or pulldowns.....

To consolidate chips consider in the future a 8-Input AND/NAND gate. See Motorola MC14501UB. Or better yet, I am going with 1 only Motorola Dual 4-Input AND Gate [MC14082B] and no inverters.

Testing:
The infomation in this section can be replaced by the rough hand written notes dated April 17, 2006

The CNC4PC literature says that the 5VDC terminals provide up to 1 amp.

When connecting the power terminals of this board directly to a CNC4PC 5VDC terminal pair the readings were;

5.01 V across the terminals.
4.82 V drop through the board.
A current draw of 4.85 MA.
This calculates to a board resistance of 1K ohms.

Outside Supplier ~ Gecko Error/Reset:

Controller; http://www.aree.com/gecko/err.html Have hard copy.

Controller Pricing; http://www.aree.com/gecko/price.html Have hard copy.

The schematic, including board layouts; http://www.aree.com/gecko/g320rev2.pdf Have hard copy.

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Last Revised: May 17, 2006