Siemens SIMATIC PCS 7 CPU 410-5H System Manual page 38

Structure of the CPU 410-5H
3.1 Operator controls and display elements on the CPU 410-5H
Rear panel of the CPU 410-5H
Setting the rack number
Use the switch on the rear panel of the CPU to set the rack number. The switch has two
positions: 1 (up) and 0 (down). One CPU is allocated rack number 0, and the partner CPU is
assigned rack number 1. The default setting of all CPUs is rack number 0.
Slot for system expansion card
The back of the CPU has a slot in which you insert the system expansion card (SEC) before
commissioning the CPU. The SEC contains information that specifies the performance class
of the CPU in terms of the amount of POs it supports. The SEC is an essential part of the
CPU hardware. The CPU cannot be operated without an SEC. If an SEC is not detected, the
corresponding CPU goes to STOP and requests a memory reset. "STOP by CPU memory
management" is also entered in the diagnostics buffer.
You need a small screwdriver to remove the SEC. Place the screwdriver at the top of the
SEC slot and lift out the SEC with the screwdriver.
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CPU 410-5H Process Automation
System Manual, 09/2014, A5E31622160-AB