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7), and the Remote Lockout flag (bit 1) of the Instrument General Flags
register 7 (address 6). Together these are referred to as the inhibit bits.
The Inhibit flags are controlled by the local unit. If the "Remote Total
Changes Disabled" flag is set, it blocks the ability of the MBM to update
or reset the totalling registers. If the "Remote Lockout" flag is set, it
blocks the ability to write and update any registers that may change the
unit's settings. This includes all writeable registers. This allows a field
technician to stop the unit's settings being changed remotely while
maintenance or fault finding is being undertaken. This setting should be
reset once the task is complete.
The general procedure for updating a unit's setting by the MBM follows
the steps below:
1. Set the "Lock-out Updates" flag as mentioned earlier.
2. Perform write operations as necessary and set respective
update flags.
3. Clear the "Lock-out Updates" flag.
4. Check the desired action has been performed by examining the
update flags. If the action has been performed, update flags will
be automatically cleared
performed, these flags will remain set.
There may be several reasons why an action has not been performed,
but the most likely cause is that there has been a race condition
between checking the inhibit bits and them being set by a local user.
The action may take up to a second to be performed. While this is occurring,
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all messages to the unit will receive a SLAVE_BUSY response.
Issue 1.1 March 2022
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, but if the action has not been
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