Pepper Computer Modular Computers RS485 - Manual (Page 319)

SMART I/O User’s Manual
©1996 PEP Modular Computers GmbH October 01, 1996 Page 6 - 37
6
Chapter 6 Communications Modules
FB_SSI_READ
In order that the current state of the encoder
may be read, this command is issued - nor
mally in a loop built into the ISaGRAF cycle.
The read-back value appears in the position
variable.
As can be seen from figure 6.2.11.1.1, the inputs to the module are displayed
on the left-hand side of the SSI block and the outputs are indicated on the
right-hand side.
setpoint
This is the register which contains the value of the
setpoint which is sent to the SSI module with the
Command statement.
port
The port register is used for setting the port number
of the attached SM-SSI Module.
ctrx
The control register elements; for a description of the
register please refer to the relevant section appearing
earlier.
error
If an error occurs then it’s value appears in this
variable.
position
The position of the encoder following a read is
recorded in this variable.
statusx
The status register elements; for a description of the
register please refer to the relevant section appearing
earlier.