Siemens SIMATIC IM151-1 STANDARD Manual page 30

Functions
3.2 Option handling without reserve modules
Note
In the case of option handling without RESERVE modules, incorrect filling in of the control
interface can result in too many plugged modules with a slot number greater than 63 are
reported from the point of view of the interface module. Since there is only room for 63
modules in the diagnostics message (module status), the highest-value bit is set in the
"Identifier-related diagnostics" in this case. This produces the following results:
- The SF LED on the IM lights up
- Bit 3 in status byte 1 of the diagnostics message is set (external diagnosis exists)
- The "Slot 64 faulty" error message is indicated in STEP7.
Behavior during the first start-up
In the case of option handling without RESERVE modules, the IM151-1 always goes into
cyclic data exchange during the first start-up. However, the I/O device input/output is not
activated until valid information about the options is available from the module. No fault is
indicated externally in this state (BF LED does not light up). The input/output of the I/O
devices is not active in this state. Evaluate the data of the feedback interface in order to
assess this state.
Behavior during a warm restart
Valid information about the options is stored retentively in the IM151-1. During the warm
restart, the IM151-1goes into cyclic data exchange and the input/output of the I/O devices is
activated immediately. Has the configuration changed since the last startup (e.g.: incorrect
module plugged in or information about options is incorrect), the input/output of the I/O
devices is deactivated (irrespective of the parameter "Mode with set <> actual setup") until
the real configuration agrees again with the configured one.
30
Interface module IM151-1 STANDARD (6ES7151-1AA06-0AB0)
Manual, 07/2015, A5E01075950-AD