Siemens SIMATIC CP 440 Manual page 17

LEDs
The following LEDs are located on the front panel of the CP 440:
INTF
EXFT
FAULT
TXD
RXD
The operating modes and faults and errors indicated by these LEDs are described
in Section 8.2. Section 5.5 contains information on the LEDs that come on when
you download firmware updates.
Interface
For a detailed description of the interface, see Section 1.4.
Base Connector for the S7 Backplane Bus
On the back panel of the CP 440 you will find the base connector for the S7-400
backplane bus.
The S7-400 backplane bus is the serial data bus via which the CP 440
communicates with the modules of the programmable controller.
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
(red) Indicates an internal fault
(red) Indicates an external fault
(red) Fault LED for interface
(green) interface sends
(green) interface receives
Product Description
1-7