G&L MMC-A2, Hardware Manual

Page: 82 / 192

Standalone MMC Control
74 MMC Hardware Manual G & L Motion Control Inc.
4.7.2.1 Isolated Breakout Box Details
The Isolated Breakout Box is different then the Standard
Breakout Box in three ways:
•
The Isolated Breakout Box provides optical isola-
tion between the encoder (A, A/, B, B/, I, I/) signals
and the Control. This boosts the encoder common
mode voltages allowed from approximately 10 volts
to hundreds of volts. This allows reliable encoder
operation in the presence of large amounts of electri-
cal noise and ground disturbances relative to the
Control.
•
Since the Isolated Breakout Box uses +5 Vdc from
pin 12 of the Control to power it’s internal circuitry,
there is no +5 Vdc current to power the encoder.
Therefore, the pin 12 screw terminal on the Isolated
Breakout Box does not carry +5 Vdc, and the
encoder must be powered by an external supply.
•
When using the Isolated Breakout Box, the “index”
inputs (I, I/) must be connected. If the connected
encoder does not provide the index function, con-
nect I on the Breakout Box to +5 Vdc, and I/ to +5
Vdc Common. Failure to connect I and I/ will result
in a “loss-of-feedback” by the Control.
Figure 4-15: Connections from Encoder to Encoder Isolated AUX I/O
Optical
Isolator
Optical
Isolator
Optical
Isolator
1
2
3
4
5
6
A+
A-
B+
B-
1
2
3
4
5
6
A+
A-
B+
B-
I+
I-
I+
I-
+5V
12 +5V
Breakout Box
Screw Terminals
MMC Connector
Pins
(I & I/ must be
connected)