Micromod MOD: 1800P - MOD 30ML Identity Module (Version 2) System, I/O and Communications Functions - Manual (Page 24)

Logic Functions - Book 1
DATABASE DESCRIPTION
2-12
error is detected, a diagnostic event will be generated, and the instrument will go to a default
state.
Checksum boundaries are every 512 bytes (128 four-byte words). When a byte is written to
memory, its address is shifted right 9 bits to produce the checksum boundary table index.
A single database write typically involves more than one byte at a time. When multibyte writes
cross checksum boundaries, the two checksum table entries are updated as required.
2.5.3 Backup Memory
The backup memory module is used to maintain a mirror image of the 64K instrument
database. A small part of this image is reserved for shutdown information and serves as a
valuable diagnostic tool.
UPLOAD From Main Database to Memory Module
The instrument attempts an upload to the memory module during power-up when the memory
module switches are set to read/write and module load. It then runs the default database with
instrument state equal to UPLOAD. LEDs will be green on, red on if successful, green on, red
flashing if unsuccessful. Diagnostics and system events may be read from instrument, but
instrument state cannot be changed until power is removed and module switch is placed in
NORMAL.
A command attribute (CMD) is provided in the Interface Block to allow a remote
operator/device to request an upload to the module. The instrument can be in any state as
the data transfer will use direct memory access with scan interrupts disabled. Diagnostics are
provided as above in case of failure.
Uploads are possible when the module is not switch or software write protected and the main
database is configured, version compatible, and has valid checksums.
DOWNLOAD From Memory Module to Main Database
If the module database is ’good’ (configured, version compatible, has valid checksums, no ICN
or comm port mismatch), the module switch is in ’normal’, the ’download on warm start’
attribute is YES and the instrument did not have a previous shutdown fault, the transfer will
occur at power up. The download on warm start attribute in the interface block allows a user
to (for instance) write protect a module with cold start values in it and have it download only on
cold start. It will default to YES in the configurator.
A command attribute (CMD) is provided in the interface block to allow a remote
operator/device to request a download from the module. Diagnostics are provided in case of
failure.
The user of the download from module command will be required to go through a protocol to
get configuration control before the command will be accepted. This will be done by setting
Next Instrument State (NXTISTAT) attribute to BEING CONFIGURED.
Shutdown Information
Instrument status information is saved in the memory module and database when the
instrument shuts down for any reason. Shutdown information can be interpreted to determine
the cause of unrecoverable errors.