DESCRIPTION AND OPERATION
FUNCTIONAL OPERATION
2 - 2
I-E96-209A
®
identifies the module. The device address for the logic master
module is set via an eight position dipswitch.
NOTE: The LMM cannot communicate over the controlway.
Slave Expander Bus Interface
The slave expander bus interface on the logic master module
allows it to communicate with up to 64 digital slave modules
that interface with additional I/O based on the user's require-
ments. The LMM reads and writes data and control informa-
tion to the slave modules over the slave expander bus. Each
slave module has a unique slave expander bus address that
must match that specified in the LMM's configuration. Dip-
shunts must be configured and installed on the MMU back-
plane between the LMM and associated slave modules. Refer to
of this manual for details.
Memory
The onboard memory is 32K bytes of read only memory (ROM),
16K bytes of random access memory (RAM) and 8K bytes of
nonvolatile random access memory (NVRAM).
The ROM contains the function code library and the operating
system. The RAM serves two purposes: holding an operating
copy of the configuration when the module is in the execute
mode of operation and providing temporary storage for in-pro-
cess algorithms. The NVRAM contains the permanent copy of
the user's configuration. The logic master module's NVRAM
has the capacity for approximately 1,024 function blocks.
Machine Fault Timer
The Machine Fault Timer (MFT) is a resettable one-shot timer
that must be periodically retriggered by the microprocessor.
Several conditions detected by the microprocessor will keep it
from retriggering the MFT. They are:
1.
Trip Block activated.
2.
Failure of ROM checksum.
3.
Failure of diagnostics at reset/power up time.
When the MFT is allowed to time-out, the microprocessor is
halted. The LMM will not respond over the module bus, and the
status LED changes to a solid red color. In addition, the digital
outputs are de-energized.
In the event of an NVRAM checksum failure, the module will
indicate error status. This means that the status LED will flash
on and off green, and will continue to execute all algorithms.
The module will enter error mode when reset.
