Siemens Simatic S7-400 - Manual (Page 79)

Racks
2-9
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
2.6 The Racks ER1; (6ES7403-1TA01-0AA0)
and ER2; (6ES7403-1JA01-0AA0)
Introduction
The ER1 and ER2 racks are used for assembling expansion racks.
The ER1 and ER2 racks have only one I/O bus with the following restrictions:
• Interrupts from modules in the ER1 or ER2 have no effect since there are no
interrupt lines provided.
• Modules in the ER1 or ER2 are not supplied with 24 V. Modules requiring a
24 V supply are not provided for use in the ER1 or ER2.
• Modules in the ER1 or ER2 are not backed up either by the battery in the power
supply module or by the voltage supplied externally to the CPU or the receive
IM (EXT.-BATT. socket).
There is therefore no advantage in using backup batteries in the power supply
modules in ER1 and ER2.
Battery faults and backup voltage faults are not reported to the CPU.
The battery monitoring function of a power supply module installed in the ER1
or ER2 should therefore always be switched off.
Suitable Modules for ER1 and ER2
You can use the following modules in the ER1 and ER2 racks:
• All power supply modules
• Receive IMs
• All signal modules provided the above-mentioned restrictions are observed.
However: Power supply modules cannot be used in conjunction with the IM 461-1
receive IM.