Metrohm 781 pH/Ion Meter: Operation via RS-232 - Manual (Page 3)

1 General rules
780/781 pH/Ion Meter - Operation via RS232
1
1 General rules
The 780 pH Meter and 781 pH/Ion Meter have an extensive remote
control facility that allows full control of the instrument via the RS232
interface, i.e. the pH/Ion Meter can receive data from an external
controller or send data to an external controller.
In most instances, the following description applies to both instruments,
780 and 781. Those sections describing concentration measurement
parameters are valid for the 781 pH/Ion Meter only.
Carriage-return (C
R
) and Line-feed (L
F
) are used as terminators for the
data transfer. The pH/Ion Meter sends 2 x C
R
and L
F
as termination of a
data block, to differentiate between a data line which has C
R
and L
F
as terminators. The controller terminates its commands with C
R
and L
F
.
If more than one command per line is sent by the controller, “;” is used
as a separator between the individual commands.
The commands are grouped logically and easy to understand. Thus,
e.g., for the selection of the pH mode, the following must be sent
&Mode.Select "pH"
whereby it is sufficient to transmit the boldface characters only:
&M.S "pH"
The quantities of the pH/Ion Meter are collected in groups, e.g.:
&Config
This group is divided in subgroups containing configuration data, e.g.:
&Config.Aux
This subgroup in turn contains the individual inquiries for auxiliaries
settings, e.g.:
&Config.Aux.Language
for setting the dialog language or
&Config.Aux.Display
for choosing the positive or negative display setting.
The data are hierarchically structured (tree form). The quantities that
occur in this tree are called objects in the following. For example, the
dialog language is an object.
If one is in the desired location in the tree, the value of the object can
be queried:
&Config.Aux.Language $Q (Q means Query)
The query command $Q triggers the output of the value from the
instrument. All entries which start with $ are thus called triggers.
Values of objects can not only be queried, they can also be modified.
Values are always entered in quotes, for example:
&Config.Aux.Language "english"