The information that is exchanged between the controller (computer) and the device (KFM2150) is called a message.
The KFM 2150 uses the SCPI language for the messages.
There are two types of messages, commands that are sent from the computer to the KFM 2150 and responses that are sent from the KFM2150 to the computer.
SCPI commands are ASCII-based commands designed for test and measurement devices. The command hierarchy is structured around the common root or node, which is the construction block of the SCPI sub system.
A command consists of a program header, parameters, and punctuations.
The hierarchy is explained using the SOURce subsystem as an example.
| Program header | Parameter | Hierarchy of node | |||
| SOUR: | Roote node | ||||
| CURRent | Second level | ||||
| [:DC] | Third level | ||||
| [LEVEL] | <numeric> | Fourth level | |||
| :EXTernal | <numeric> | Fourth level | |||
| VOLTage | Second level | ||||
| [:DC] | Third level | ||||
| :PROTection | Fourth level | ||||
A higher node is separated from a lower node using a colon (:).