Catalog ST PCS 7.1 - September 2005

7
Distributed I/O on the PROFIBUS
AddFEM: Redundant distributed I/O module for
fast response times
■ Overview
The Front End Module AddFEM is an autonomous unit for the input/output
of analog and digital process signals that can be connected
with standardized protocols via the PROFIBUS DP fieldbus
to the SIMATIC PCS 7 automation system.
In addition to the AddFEM basic version, the product range also
comprises special product versions implemented with an intelligent
front end function (FEF) (AddFEM PoCo, AddFEM SoE) or
based on the stand-alone hardware (AddFEM HART):
• AddFEM PoCo is designed for fast position control.
• AddFEM SoE (Sequence of Event) has 31 digital inputs with
highly accurate time tagging.
• AddFEM HART is a redundant I/O module for operation with
sensors and actuators with HART capability.
■ Benefits
• The redundantly operable AddFEM has particularly fast response
times for signal recording, processing and redundancy
switching (switchover time less than 500 µs).
• The AddFEM has extended level ranges for analog signals
and counters.
• The analog and digital areas are electrically isolated from one
another.
• All outputs are monitored and can be switched in parallel with
other outputs (redundancy, performance increase).
• Analog and digital outputs are permanently short-circuitproof.
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Siemens ST PCS 7.1 · September 2005
■ Design
Built into a rugged high-grade steel housing, which is in line with
the SIMATIC S7 design in terms of dimensions and shape, the
AddFEM meets stringent environmental requirements. It is prepared
for mounting on DIN rails and for direct mounting with
bolts. These installation options support both freestanding construction
and installation in cabinets or wall-mounted housings.
The connecting elements are protected by a removable hood on
which the connector pin assignment of the peripheral signals is
printed. The functions are set by means of two mode selectors
and indicated by 12 LEDs. In accordance with the PLC standard,
2 x 16 LEDs are available in the display panel of the module
for signaling the binary I/O signals.
■ Function
The AddFEM is equipped with the following process connections:
• 12 analog inputs
• 8 analog outputs
• 12 digital inputs
• 3 timer inputs (can also be configured as digital inputs)
• 16 digital outputs (can also be configured as digital inputs)
The AddFEM PoCo offers:
• 8 positioners
The AddFEM SoE has:
• 31 digital inputs with time tagging
The AddFEM HART has:
• 24 analog inputs with HART capability
• 8 analog outputs with HART capability
• 8 power supplies for four-wire transmitters (can alternatively
be used as digital outputs)
The various signal types are distributed across the process connections
in such a way that small applications can be executed
with a single module. Applications with a large quantity framework
can be implemented by using several modules. The measuring
ranges of the analog inputs and outputs are designed so
that when using the AddFEM, e.g. for turbine controllers, no additional
signal transducers have to be used. By means of an additional
current range of ± 50 mA for the analog outputs, additional
actuators with a higher required drive power, e.g. fuel
control valves, can also be controlled without additional signal
amplifiers.
The 24 analog inputs and 8 analog outputs of the AddFEM
HART are recorded and output in a fast cycle of 833 µs. Transmission
of additional signals via HART protocol and monitoring
of the transmitters are carried out parallel to this in a 2-s cycle.
The AddFEM HART is integrated in SIMATIC PDM and in the
PCS 7 Asset Management.