HP 8360 manual Figure l-25. a Simplified Command Tree, Paths Through the Command Tree

rootc

level 1	BB	c c	DD
	+I		rtl
level 2	EE FF	GG	HHJJ

Figure l-25. A Simplified Command Tree

In the command tree shown in Figure l-25, the command closest to the top is the root command, or simply the root. Notice that you must follow a particular path to reach lower level subcommands. For example, if you wish to access the GG command, you must follow the path AA to BB to GG.

Paths Through the Command Tree

To access commands in different paths in the command tree, you must understand how an instrument interprets commands. A special part of the instrument firmware, a purser, decodes each message sent to the instrument. The parser breaks up the message into component commands using a set of rules to determine the command tree path used. The parser keeps track of the current path, the level in the command tree where it expects to find the next command you send. This is important because the same keyword may appear in different paths. The particular path you use determines how the keyword is interpreted. The following rules are used by the parser:

8 Power On and Reset

After power is cycled or after *RST, the current path is set to the root.

nMessage Terminators

A message terminator, such as a <new line> character, sets the current path to the root. Many programming languages have output statements that send message terminators automatically. The paragraph titled, “Details of Commands and Responses,” discusses message terminators in more detail.

8Colon

When it is between two command mnemonics, a colon moves the current path down one level in the command tree. For example, the colon in MEAS:VOLT specifies that VOLT is one level below MEAS. When the colon is the first character of a command, it specifies that the next command mnemonic is a root level command. For example, the colon in : INIT specifies that INIT is a root level command.

l-68 Getting Started Programming