Lake Shore Cryotronics Measure Ready M91 FastHall, User Manual

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56 c
HAPTER
4: Computer Interface Operation
MeasureReady™ M91 FastHall™ Measurement Controller
4.2.1.2 Subsystem
In addition to the common commands, SCPI defines subsystem commands. If the
M91 FastHall™ measurement controller is considered a “system”, then the logical
grouping of its various functions can be considered different “subsystems”, forming a
hierarchical “tree”. Each subsystem is comprised of program headers. Together, these
comprise the individual SCPI command. The following is an example of several M91
SCPI commands and how they fit into the hierarchical tree:
:DISPlay
:BRIGhtness <brightness>
:ENABle <bool>
4.2.2 Queries Many times, a command will have a corresponding query. Queries require a question
mark at the end of the command header. If a query requires a parameter, place the
question mark at the end of the header and before the query parameters.
4.2.3 Optional
Commands If a command header is enclosed in brackets ([ ]), then it is optional. Do not include the
brackets if you send the optional command to the instrument. For example, the fol-
lowing command messages are both valid, since the AUTO header is optional:
CCHeck:STARt:AUTO
CCHeck:STARt
4.2.4 Short and Long
Form SCPI specifies a short and long form for its command headers. The command header is
completely spelled out in the long form while it is abbreviated to the first three or four
letters for short form. The following is an example of the same command in both short
and long form:
CCHeck:STARt
CCH:STAR
4.2.5 Number Suffix When a command header is used to represent multiple instances of a given function
of the instrument, the selection of which to use is designated by a numeric suffix
attached to the command header. This suffix is applicable for both short and long
forms.
Examples:
DIGital:OUTput1:FUNCtion MANual
DIG:OUT2:FUNC TRIG
4.2.6 Multiple
Commands in a Single
Message Many times, it is desirable to chain multiple commands and queries together into one
message transmission. To do this, separate each command/query with a semicolon
and be sure to include a colon before the next command, unless it is a common com-
mand which uses the “*” prefix.
If multiple commands are provided in a given message, the M91 will process the com-
mands in the order in which they were received. Subsequently, if multiple queries are
included in chained message, the M91 will respond to the queries in the order in
which they were received.
As an example, the following command message sets the analog output to 10 V, will
query the contact check results, resistivity results, and request a response of “1” once
all the commands are processed.
Sent:
ANALOG:OUTPUT:SETTING 10;:CCH:RES:JSON? 1;:RES:RES:JSON?
1;*OPC?
Received:
10