ROTRONIC MBW 373 - Manual (Page 38)

34
Command Syntax
This section details the general syntax guidelines regarding termination, leading and trailing
spaces, case sensitivity, and numeric values. Throughout this section, characters originating
from the computer will be shown for illustrative purposes in this font. Characters
originating from the 373 will be shown in this font.
General Usage
All commands require either a question mark or an equal sign to indicate whether you are
requesting data or setting new setpoints or parameters. When requesting data from the 373,
follow the command with ?, the question mark character. For example, the following requests
the current Automatic Mirror Check timing interval..
AMC.cycleTime?
The 373 replies with the current AMC cycle time. This value may have been entered from the
touch screen or as you will now see, via RS-232.
When setting new values or parameters, use =, the equal sign. For example, the following
command changes the Automatic Mirror Check timing interval to 20 minutes.
AMC.cycleTime=20
Most commands that can be set with an equal sign, such as the one in the above example,
may also be read with the question mark. That makes sense. However, there are several
commands that are considered read only, and have no corresponding ability to be set.
Examples of read only capability are measured parameters, such as dew point, frost point,
RH, etc.. While it is perfectly valid to read dew point with a command such as dp?, it
obviously makes no sense to be able to set the dew point value. Therefore, a command such
as dp=1.23 is considered invalid, and will be ignored by the 373.
Termination Characters
All commands must be terminated with either a carriage return C
R
or a carriage return linefeed
combination C
R
L
F
.
Regardless of the command sent, the 373 will reply with a carriage return linefeed
C
R
L
F
at the
end of the response, provided the command is recognized as valid. Here is an example:
DP? C
R
(sent by the computer to the 373)
-10.015 C
R
L
F
(sent by the 373 back to the computer)
Even if the command is not a request for data, but rather is a command to change a setpoint
or parameter, the 373 still responds with a carriage return line feed combination. The
following turns on the pump (if your unit is so equipped). Notice that no data is returned, but
the 373 sends a
C
R
L
F
acknowledgement that the command was valid.
Pump.on = 1 C
R
(sent by the computer to the 373)
C
R
L
F
(the acknowledgement from the 373)
However, if the command is unrecognized, the 373 does not respond. See the example.
Abcdef? C
R
(invalid command sent from the computer)
(no response from the 373)