Functional Description - PEP Modular Computers Modular Computers RS485 User Manual

Chapter 6 Communications Modules

6.2.5 Functional Description

Figure 6.2.5.1: SM-SSI Schematic Diagram
BU1
SPI
STXD
SRXD
SCLK
SPI Bus
SCS
P1-5
I/O
Lines
NRESET
Reset
Line
NINT
Int
Line
VCC
GND
The Synchronous Serial Interface working together with a photographically
etched encoder disk allows absolute codes (positions) of rotating axis to be
continuously monitored. The greatest advantage of the SSI communication
process compared to that of standard serial/parallel procedures is that the
controller actually regulates the timing and speed of the data transmission
which further optimizes data security.
Simplicity in design with low conventional component count coupled with
the inherent safety offered through accurate axis position reading even after
power fail, enable this compact module to be utilized for equipment operat-
ing even in extreme environmental conditions.
October 01, 1996
EEPROM
SPI
SSI
Interface
Interface
+
Selection
Decoder
Last Value
(24-bit)
Control
Logic
+
Comparator
Status
Board ID
Comp. Value
Data
(24-bit)
Configuration
SPROM
©1996 PEP Modular Computers GmbH
SMART I/O User's Manual
OPTO
OPTO
RC +
OPTO
Schmitt
RC +
OPTO
Schmitt
OPTO
OPTO
OPTO
FPGA
LED 0 LED 1
Data Flow Match
BU1
Analog
SSI
Clock +
Clock -
Data +
Data -
End of
range
switches
EOR1
EORCOM2
EOR2
Encoder
Control
Direction
Reset
Com+
Match
6
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