Specifications

AS-Interface Master
Master for SIMATIC S7
CP 243-2
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Siemens IK PI · 2009
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■ Overview
The CP 243-2 is the AS-Interface master for the innovated
generation of SIMATIC S7-200. The communications processor
(6GK1 243-2AX01-0AX0) supports the extended AS-Interface
specification V2.1 and has the following functions:
• Up to 62 AS-Interface slaves can be connected and inte-
grated analog value transfer (according to the extended
AS-Interface specification V2.1)
• Supports all AS-Interface master functions in accordance with
the extended AS-Interface specification V2.1
• Status displays for operating states and display of the func-
tional readiness of connected slaves with LEDs in the front
panel
• Indication of errors (incl. AS-Interface voltage errors,
configuration errors) with LEDs in the front panel
• Compact enclosure designed to match the new generation of
SIMATIC S7-200.
■ Benefits
• More flexible and extended application options of the
SIMATIC S7-200 due to the considerable increase in the
available digital and analog inputs/outputs
• Shorter startup times due to easy configuration at the press of
a button
• In the event of a fault, shorter standstill and service times due
to LED indication of:
• Status of the CPs
- connected slaves and their operational readiness
- monitoring of the AS-Interface voltage level
■ Application
The CP 243-2 is the AS-Interface master connection exclusively
for the CPUs 22x of the innovated SIMATIC S7-200 generation.
By connecting to AS-Interface, the available digital inputs and
outputs for S7-200 are significantly increased (max. 248 DI /
186 DO on AS-Interface per CP).
In addition, the integrated analog value processing also makes
analog values (per CP max. 31 analog slaves, each with up to
4 channels) available to the S7-200 at the AS-Interface. Up to
two CP 243-2s can be operated simultaneously on the S7-200.
■ Design
The CP 243-2 is connected to the S7-200 like an expansion
module. It features:
• Two terminals for direct connection of the AS-Interface cable
• LEDs in the front panel for displaying the operating status and
the operational readiness of all connected and activated
slaves
• Two 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 243-2 supports all of the specified functions of the ex-
panded AS-Interface specification V2.1. This makes it possible
to operate up to 62 digital slaves or 31 analog slaves on the
AS-Interface by means of duplicate address assignment (A-B).
Access to the analog values is just as easy as accessing the
digital values thanks to the integrated analog value processing.
In the process image of the S7-200, the CP 243-2 occupies a
digital input byte (status byte), a digital output byte (control
byte), 8 analog input words and 8 analog output words. This
means that the CP 243-2 occupies two (logical) slots. Using the
status byte and the control byte, the mode of the 243-2 can be
set in the user program.
Depending on the mode, the CP 243-2 saves either the digital or
analog I/O data of the AS-Interface slaves or diagnostic values
in the analog address space of the S7-200 or allows the master
calls (e.g. changes to the slave addresses).
Configuration
All of the connected AS-Interface slaves are configured by
the press of a button. No further configuration of the CP is
necessary.