Introduction
Copyright IXXAT Automation GmbH
16
IEM Manual, 1.5
1.8.1 Working principle
The IEM is mechanically and electrically connected to the host application pro-
cessor by the Board-to-Board Connector. The FPGA design incorporates
amongst other components a dual ported memory (DPRAM) and a NIOS II
soft-core processor. This DPRAM serves as a shared memory over which the
communication between the IEM’s NIOS II processor and the host application
processor is handled.
1.8.2 Ethernet ports
The IEM provides two galvanic isolated RJ45 female connectors. The con-
nectors are designed to fulfill all mandatory requirements from the various in-
dustrial Ethernet specifications (PE, Shield, PHY, etc.). All Ethernet communi-
cation is handled completely by the IEM itself.
1.8.3 Board-to-Board Connector
The IEM is connected through a 50-pin 1.27 mm Board-to-Board Connector
which carries all control signals, address/data bus signals as well as the power
supply for the IEM.
The Board-to-Board Connector contains all signals to connect to the host CPU
either using an address and data bus (16 bit wide on IEM, 16/32 bit wide for
design-in) or SPI. Additionally, a reset pin as well as two general purpose pins
from and to the IEM, which can be used e.g. for IRQ are provided on the con-
nector.
1.8.4 Memory interface
Seen from the application CPU’s point of view the application interface is a
block of (dual ported) memory which contains a command channel, process
data interface and several data queues.
The DPRAM can be either accessed directly (memory mapped access) or via
SPI (indirect access). To realize consistency with SPI communication, a mirror
buffer on the host is used for the communication interface.
The software running on the IEM and the library provided for the host proces-
sor separate this memory into dedicated parts used for specific communication
tasks. The main differentiation is made between exchange of process data and
all other communication. The latter is thus in the following just referred to as
“communication” (see Figure 1-2).