EC9830 CO ANALYZER OPERATION MANUAL
4-14 98307600 Rev. C-1
I.D., it processes the command and responds appropriately. The integrity of this
method relies on a strict enforcement of the following rules:
Each unit in the multidrop must have a unique I.D. that is programmed into
the unit before attaching to the network.
After a command is sent by the master, the master must then wait for a
response. Only after a reasonable time-out period should the master send
another command.
The multidrop master must include a time-out mechanism in the event that the
I.D. sent with the command is garbled. Clearly a <NAK> on a bad I.D. is not
possible for the units in this scheme.
The master must correlate the unit response with I.D. sent in the command to
know which unit in the multidrop is responding.
Any command that would cause two units on the multidrop to respond at the
same time must be avoided. If more than one unit attempts to respond on the
common transmit line, a data collision will occur destroying both messages.
4.4.4.2 Programming Instrument Identifiers
Note
The Instrument ID, or Main Gas ID, can be set
manually in the Instrument Menu or the Interface
Menu. Refer to section 2.5.3 for further details. This
is this preferred method.
Alternatively, the command PI is the only command used to set the Instrument
I.D. for a given analyzer. The instrument can then be used standalone or as one of
several multidrop (daisy-chain) analyzers. The format of this command is:
PIXXX YYY<CR>
Where:
XXX is the unit I.D.
YYY is the secondary unit I.D.
The parameter XXX is the unit I.D. and must be three characters.
Unit I.D.'s such as 1 should be programmed as 001.
For the 9841 the YYY parameter is the second unit I.D. and may be used for
any command query. This is in support of existing Bavarian networks.
Only one analyzer at a time may be programmed with an I.D. Do not issue
this command with multiple units on a multidrop.
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