Torchmate
CNC
I/O
Expansion
Board
Guide
9
The analog outputs on this 8-Pin RJ-45 connector are often used to control a variable
frequency drive (VFD) or a variable speed spindle. The connector will accept any standard
CAT-5 cable connector (RJ-45 Ethernet plug, 8 position/8 pin).
The analog output connector, as seen from the rear of the signal generator, is arranged as
shown in Table 3. The pin orientation is shown in Figure 7 to the right.
Table 3: Analog Output Connector
Pin Functions
RJ-45
Pin No.
Signal
1 +12V
2
SPON (Output 9)
3 GND
4
SPDIR (Output 10)
5 5-24V
Input
6 DACOUT0
7 GND
8 DACOUT1
Figure 7: terminated CAT-5 cable and
RJ-45 jack showing pin orientation.
Pin 1 is a +12V output that can be used as a reference voltage for the analog output circuit as
discussed below. This pin can source up to 20 mA. Any larger current demand would
require a separate external power source.
Pins 2, 3, 4, and 5 represent two push-pull output circuits. The external voltage applied at the
5-24 V input on Pin 5 will be delivered to the SPON and SPDIR pins when each is activated.
This external voltage can also be applied at TB71. For example, Pin 5 can be su24V
in order to d24V from SPON when Output 9 is activated in the Torchmate CNC
software. The SPON (Output 9) and SPDIR (Output 10) of the RJ-45 connector are logically
identical to Output 9 and Output 10 on the 10-pin Molex connector. The SPON and SPDIR
outputs can each handle up to 250 mA.
Pins 6, 7, and 8 express the two 12-bit analog output channels. These circuits are able to
deliver 0 – 10V DC divided over 4,096 (2
12
) levels approximately 2.5mV apart. They are
typically used to control spindle speed or other devices that require a variable voltage input.
The analog output circuitry can be calibrated using the OFFSET and GAIN potentiometers
on the USB I/O Expansion Board. See “Calibrating the Analog Output” for a detailed
procedure on calibration.
To facilitate external wiring, an 8-pin breakout box may be
obtained from Radio Shack (p/n 279-411). See figure 8. The
box has a screw terminal for each of the eight pins. The part
may be purchased online at www.radioshack.com. A standard
CAT-5 drop cable can be used to connect the 279-411 to the
USB I/O Expansion Board.
Figure 8: Radio Shack 279-411
