Spindle control and additional IO research

The CNC4PC board is near capacity in terms of IO. There is only one input and one output available. This makes it impossible for the moment to add the Variable Frequency Drive (VFD) for controlling a 3phase spindle motor and to add a front panel control interface for spindle, coolant pump etc.

A possible solution would be to add additional IO via ModBus over serial with or without an additional dedicated spindle control board. The ABB ACS 141 VFD requires a 0-10V control signal for speed and 12V logic for enable, direction and start/stop.

IO solutions:

http://www.henriksplace.se/pic/pic_projects/minimodbus/pic_minimodbus.html

• 4 digital inputs, opto-isolated, with LED indicator. 
• 4 digital outputs, open collector, 500mA, LED indicator, protection diode. 
• 2 analog inputs, 0-5V, 10bit resolution. 
• 1 analog output, 0-10V, 10mV resolution, 50mA drive capabillity. 
• Wide operating voltage range, 15-30V 

http://www.homanndesigns.com/store/index.php?main_page=product_info&cPath=2&products_id=4





The I/O capability of the ModIO is;
Firmware upgradeable via Serial port.

• 8 discrete inputs. Active low with internal pull-ups 
• 8 discrete outputs capable of driving relay coils 
• 2 MPG inputs that use discrete inputs 3&4 and 5&6 
• 3 Analog inputs, 0 -5v dc, 10 bit resolution 
• 1 Character LCD driver for 20x4 LCDs 
• 1 Interface for DigiSpeed controller 
• 1 Expansion bus interface for adding additional I/O modules. (to be added) 

Spindle control solutions:


http://www.cnc4pc.com/Store/osc/product_info.php?cPath=25&products_id=303

• Inputs a PWM and outputs an analog 0-10VDC.
• Has two relays that can be used to control the direction and enable and disable the drive. 
• Uses only two pins, one for PWM and one for direction. It is the presence of absence of the valid PWM signal what would start/stop the spindle. 
• Jumper to select mode of operation, US or International mode. On US mode, one relay would be used to start CW and the second one to start CCW. On International mode Relay 1 will start/stop, and Relay 2 will determine the direction of rotation. 
• Optoisolated output signals. The analog and CW/CWW signals are optically isolated, so this board can be used with drives that make grounds common with the mains that drive the VFD or motor. 
• RJ45 Connector fast installation.

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FTDI CABLE USB RS485 WIRE END 1.8M
RS485 USB to bare wire connector for controlling the ABB 9xxx series with RS485 adaptor
DigiKey part: 768-1041-ND
$36.14