Overview of Messages
The information that is exchanged between the controller (computer) and the device (PLZ-4W/PLZ-4W L/PLZ-4WH) is called a message.
The PLZ-4W/PLZ-4WL/PLZ-4WH uses the SCPI language for the messages.
There are two types of messages, commands that are sent from the computer to the PLZ-4W/PLZ-4WL/PLZ-4WH and responses that are sent from the PLZ-4W/PLZ-4WL/PLZ-4WH 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|
A higher node is separated from a lower node using a colon (:).
This manual denotes SCPI commands using the following format.
SCPI commands can be issued using the short form. The short form of a SCPI command is the section of the command written in uppercase.
SCPI commands can be sent in the long form or short form. Since SCPI commands are not case-sensitive, CURR, Curr, and curr are all accepted as the short form of CURRent. In the long form, CURRENT, Current, and current are all acceptable.
• A space is required between the program header section and the parameter section.
• Multiple parameters, when available, are concatenated using commas.
SOURce:CURRent MINimum;VOLTage MINimum
In the second command, SOURce is omitted. This is because the path is set to SOURce by the first command SOURce:CURRent MINimum.
This compound command is the same as entering the following commands.
An error occurs if a node that is not defined in the current path is designated.
Commands of different subsystems can be concatenated using a colon and a semicolon together.
This compound command contains two root nodes, SOURce and MEASure.
When the second or subsequent command starts with a colon, the path specified by the previous command is cleared.
• The maximum number of characters that can be transmitted in a single line is 256.
Special symbols used in this manual to describe SCPI commands are defined below.
• Characters and numbers delimited by "|" in braces indicate that one of the items is to be selected.
Do not include the braces in the actual program.
• The characters <> indicate program data.
Do not write <> in the actual program.
• Brackets indicate option data.
When option data is not sent with the program, the default value is applied.
Do not write [ ] in the actual program.
The device settings or status can be queried.
To make a query, add a question mark at the end of the program header section.
If a query has parameters, enter a space after the question mark followed by the parameters.
A response returned as an answer to a query. It is a message that is always sent from the device to the computer. The status of the device or measured values are transmitted to the computer.
|When transmitting two queries in separate lines, read the response to the first query before transmitting the second line.|
|• GPIB and USB|
When two query lines are sent at once, a SCPI error (-410, "Query INTERRUPTED") may occur.
When two query lines are sent at once, an incomplete response may be received for the first query followed by a complete response for the second query.
All commands must be terminated using a valid terminator.
The available terminators are <new line> (ASCII 0x0A) and EOI (end-or-identify). Either one can be used as a terminator.
EOI is not available on the RS232C. Be sure to use <new line>.
EOI is also not available on the USB. However, a terminator separate from <new line> is automatically added. It does not matter whether <new line> is added or not.
When a command string is terminated, the path is reset to the root level.
|CR (ASCII 0x0D) is not a terminator.|
The IEEE-488.2 and SCPI standards contain a set of common commands for reset, self-test, and other functions. These common commands always start with an asterisk. The commands may have one or multiple parameters.