User's Manual

Serial communication protocol
3.5.3.1 Data Acquisition, Outputs and Operation Modes
Data acquisition is comprised of three main parts:
1. definition of physical channels ,
2. definition of computations,
3. definition of logical channels.
First the sensor type and conversion to engineering units are configured into the so
called physical channel (see PC command). Then a computation needs to be
defined that will take the data from the physical channel, process the data and,
assigns it to a logical channel (see CALC command). The logical channel then
contains configurations about actions to be performed under certain conditions
(see LC command):
1. saving the result,
2. generating a notification,
3. switching an output,
4. triggering an operation mode change.
The conditions used for triggering actions have to be defined in the condition table
(see COND command)
In order to be able to switch an output, a so called output channel has to be
configured (see the OC command). Such an output channel can either be switched
automatically (via logical channel) or manually (see SWITCH command).
The A740 addNODE provides three different operation modes, each of which can
be configured to best suit a certain set of parameters. The first operation mode
(also referred to as Normal Mode) is mode number 0 and is the initial operation
mode. Operation mode changes are initiated when data is transferred to a logical
channel (see LC command). Depending on the operation mode different data
acquisition rules can be set (e.g., different sampling intervals can be used, more or
less sensors than in normal mode can be sampled, etc.). For further information
see the <modemask> parameter which is described in more detail in section
3.5.3.2.
Operation modes 1 and 2 have no special meaning and are referred to by their
numbers only. These are at your disposition and allow you to specify different
sampling intervals and event handling (e.g., one of these modes could be used as
“power saving mode”, while the other one could be used as an emergency mode,
etc.)
3.5.3.2 Table commands
With the A740 devices a new class of commands, the table commands were
introduced. They share a common similar syntax, which is by far more flexible than
the syntax used for commands up to now. The general syntax for table commands
and its meaning are as follows:
• <command> list whole config
• <command> <nr> list config entry for given element
• <command> <nr>+ list next used id's config entry, beginning with <nr> (if
<nr> is used, return <nr>!)
• <command> ? return size of table and the number of used entries
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