Adept SmartMotion - Manual (Page 38)

Chapter 2 - System Installation
38 Adept SmartMotion Installation Guide, Rev. C
2.12 MP6 Encoder (MP6-E) Panel Wiring
Encoder Compatibility
The MP6-E is used to interface to the encoders. It supports up to six encoder channels,
with differential input (A, B and Index) for each encoder. Each channel is designed to
interface directly to encoders which use industry standard AB quadrature outputs and an
optional zero-index channel. The encoder input circuitry is compatible with encoders
using differential line driver outputs (RS-422 signal, +5VDC). (Alternatively, 5V
single-ended outputs may be used, but they will be much more sensitive to external
electrical noise. For information on compatibility with other types of encoders, please
consult Adept Customer Service.) Adept strongly recommends using differential
encoders, with index pulse.
Each of the six encoder channels has its own 9-pin female D-connector located on the
MP6-E. Refer to
Figure 2-7 on page 28 for the physical location of each connector.
Connecting Power to the Encoders
All encoder inputs for the sMI6 use a scheme similar to an RS-422 differential receiver
based on industry standard 75175 integrated circuits. The difference is that a custom
resistor network and two differential receivers are used on each of the A and B inputs.
This scheme allows for the detection of broken or shorted encoder wiring. See
Figure 2-11
on page 41 for a schematic.
The encoder inputs for the previous Adept MI6 product are optically isolated at the MI6
module. This provided the ability to use different power supplies for different channels
with no common ground. Although this provided some noise immunity, it was at the
expense of a slower input pulse rate due to the slow switching speed of the optical inputs.
To provide higher encoder pulse rates, the sMI6 was designed with standard RS-422
receivers to replace these optical isolation components.
In order to maintain compatibility with the Adept MI6, all encoder power must be
supplied by an external source. Power for each encoder can be supplied from
independent power supplies or from one common power supply. However, all encoder
power supply commons must be connected together and must be connected to the sMI6's
24V power input common. Encoder power should be supplied from a source that remains
on when High Power and/or Drive Enable is off. This eliminates the need to re-calibrate
the mechanism after High Power has been cycled off.
Adept strongly recommends using shielded, twisted-pair cable for all encoder and power
connections. The MP6-E can be used to distribute power to the encoders. The power,
voltage, and current required depend upon the encoders chosen by the user. If one
common power supply is being used for all encoder channels, the power source is
connected to the “Encoder Pwr” terminal on the lower section of the MP6-E. The encoder
power supply should not be used to power other equipment, because this may cause
electrical interference to the encoder signals.
If separate power is desired for any of the encoder channels (for example, if any of your
encoders require different supply voltages), power connections must be made directly to
that encoder. The encoder input circuitry on the MP6-E does not require power from an
external supply.