Specifications

AS-Interface Master
Master for SIMATIC S7
CP 343-2
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Siemens IK PI · 2009
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■ Overview
The CP 343-2 is the AS-Interface master for the SIMATIC S7-300
PLC and the ET 200M distributed I/O device. The communica-
tions processor has the following functions:
• Up to 62 AS-Interface slaves can be connected and inte-
grated analog value transfer (according to the AS-Interface
specification V3.0)
• Supports all AS-Interface master functions in accordance with
the AS-Interface specification V3.0
• Status displays of the operating statuses and display of the
operational readiness of connected slaves with LEDs on the
front panel
• Error displays (such as AS-Interface voltage errors, configura-
tion errors) with LEDs on the front plate
• Compact enclosure in SIMATIC S7-300 design
■ Benefits
• Shorter startup times due to easy configuration at the press of
a button
• Flexible decentralized topologies can be constructed by us-
ing this communications processor in the ET 200M DP slave.
• Reduction of standstill or service times in the event of a fault
through LED displays:
- status of the AS-Interface network
- connected slaves and their operational readiness
- monitoring of the AS-Interface voltage level
• Reduced costs for spare parts inventories because the CP
can be used in both the SIMATIC S7-300 and in ET 200M.
• Ideal for complex applications through the connection option
of 62 slaves and integrated analog value processing
■ Application
The CP 343-2 is the AS-Interface master connection for SIMATIC
S7-300 and ET 200M. The connection to the AS-Interface per-
mits a maximum of 248 DI/248 DO to be accessed for each CP.
The integrated analog value processing also enables analog
signals to be evaluated very easily (max. 62 analog slaves each
with max. 4 channels per CP, or max. 2 channels in the case of
A/B analog slaves).
■ Design
The CP 343-2 is connected to the S7-300 like an expansion
module. It features:
• Two terminals for direct connection of the AS-Interface cable
• LEDs in the frontplate for displaying the operating status and
the operational readiness of all connected and activated
slaves
• Pushbuttons for displaying the status information of the
slaves, for switching the operating status and entering the ex-
isting ACTUAL configuration as the SETPOINT configuration
■ Function
The CP 343-2 supports all of the specified functions of the AS-
Interface specification V3.0. This makes it possible to operate up
to 62 digital or analog slaves on the AS-Interface by means of
extended address assignment (A/B). The integrated analog
value processing allows easy access to the analog values.
The CP 343-2 occupies 16 byte each in the I/O address space
of the SIMATIC S7-300. In this space, the digital I/O data of the
standard or A-slaves are stored. The I/O data of the B-slaves and
the analog I/O data can be accessed using the S7 system func-
tions for reading/writing data sets.
A- and B-slaves are slaves in accordance with the AS-Interface
specification V2.1 or V3.0.
If necessary, master calls can be performed using the command
interface FC ASI_3422, e.g. read/write parameter, read/write
configuration. The FC, including STEP 7 sample program, can
be downloaded from the Internet at
http://support.automation.siemens.com/WW/view/com/5581657
Configuration
All of the connected AS-Interface slaves are configured by
the press of a button. No further configuration of the CP is
necessary.