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Torchmate
CNC
I/O
Expansion
Board
Guide
10
Spindle Feedback Control (“ENCODER” in Figure 4)
This 8-Pin RJ-45 Connector is used for spindle encoder input, most commonly as spindle
speed feedback to read the spindle speed in real time and to control threading operations on
CNC lathes. A CAT-5 cable connector (standard Ethernet drop cable) will plug into this
receptacle. For your convenience during the wiring process, you may choose to purchase an
8-pin wiring block from Radio Shack (p/n 279-411) as described in the Analog Output
section. This device provides break-out screw terminals for all 8 pins and it can be obtained
from www.radioshack.com.
The spindle encoder inputs A, B and INDEX may be single-ended or differential and they
may be connected to single channel or quadrature encoders. The index pulse is not
absolutely necessary, but it comes in handy if you have to re-start a thread already in
progress or if you have a high-resolution encoder and a high spindle speed.
The encoder signal requirements are as follows:
1.
TTL Level Signals (0, 5V) for each channel
2.
Single ended (A) or differential signals (A+ and A-) acceptable.
3.
Single channel (A) or 2 channel (A+B Quadrature) acceptable.
4.
Index pulse accepted, but not required
5.
16 to 2048 CPR (contact Torchmate for support using encoders under 100 CPR)
Table 4 shows the pin assignments for this connector and Figure 9 at right shows the pin
orientation.
Table 4: Spindle Feedback/Control
Connector Pin Functions
RJ-45
Pin No.
Signal
1 CH
A-
2 CH
A+
3 CH
B-
4 CH
B+
5 +5V
6 INDEX+
7 GND
8 INDEX-
Figure 9: terminated CAT-5 cable and
RJ-45 jack showing pin orientation.
Figure 10 shows a plan view of the USB I/O Expansion Board with the external connectors
highlighted. Note that there are two RJ-45 connectors on the USB I/O Expansion Board that
are used for two different purposes.