Ssi Operation - PEP Modular Computers Modular Computers RS485 User Manual

SMART I/O User's Manual

6.2.6 SSI Operation

With reference to figures 6.2.6.1 and 6.2.6.2, the operation of the SSI inter-
face will be discussed.
• The position of the encoder disk is continuously clocked.
• Position data is ready for conversion by the parallel -> serial converter.
• The controller (SM-SSI) demands the axis angle from the encoder
which starts the SSI clock - the number of clock pulses required is
dependent on the data width (24-bits).
Figure 6.2.6.1: SM-SSI Timing Diagram
1 2
Clock
Serial Data
Monoflop P/S*
Parallel Data
m - 1 m
m = Stored parallel data
td = Delay time for the first clock
Gn = MSB of Gray* code
Tp = Pause time in SSI clock
* Binary code may also be converted.
Page 6- 20
T
td
Gn Gn - 1
m
m + 1
©1996 PEP Modular Computers GmbH
Chapter 6 Communications Modules
3
tm
G 1 G 0
T = SSI clock period
G0 = LSB of Gray* code
tm = Monoflop time
4
Tp
October 01, 1996