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User Manual
E727T0005, valid for E-727
BRO, 2019-06-28
Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Page 144 / 240
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email
SPI Interface
Definition of Terms
PI-controller: E-727, the SPI slave.
Host: SPI master device which sends commands to the PI-controller.
Overview
The serial data transfer via SPI is primarily designed for transferring position data from and to the
PI-controller with minimum latency and update rates as high as the servo frequency of the PI-
controller.
It is also possible to send and receive ASCII data so that the host has full access to the PI General
Command Set (GCS).
The following block diagram shows the architecture on PI-controller side. The signals shown in this
diagram are described in the following sections.
The PI-controller sends current position data to the host and receives new target position data
from the host (for configuration options, see p. 145). For that purpose data segment 1 is used.
For transferring GCS commands data segment 2 is used.
As long as no responses to GCS commands are sent the PI-controller can send flags, for example
OnTarget-flags.
All transfers are initiated by the host.