KEPCO MST 488 Programmer - Manual (Page 38)

3-12
MST488-27 013004
3.4.7 PROGRAM MESSAGE SYNTAX SUMMARY
• Common commands begin with an asterisk (*).
• Queries end with a question mark (?).
• Program messages consist of a root keyword and, in some cases, one or more message
units separated by a colon (:) followed by a message terminator. Several message units
of a program message may be separated by a semicolon (;) without repeating the root
keyword.
• If a program message has more than one message unit, then a colon (:) must precede
the next keyword in order to set the parser back to the root (otherwise the next keyword
will be taken as a subunit of the previous message unit).
e.g., the command
meas:volt?;curr?
will read output voltage and output current
since both
volt?
and
curr?
are interpreted as subunits of the
meas
command.
• Several commands may be sent as one message; a line feed terminates the message.
Commands sent together are separated by a semicolon (;). The first command in a mes-
sage starts at the root, therefor a colon (:) at the beginning is not mandatory.
e.g., the command
meas:volt?;:curr?
will read output voltage and programmed cur-
rent since the colon preceding
curr?
indicates that
curr?
is not part of the
meas
com-
mand and starts at the root.
• UPPER case letters in mnemonics are mandatory (short form). Lower case letters may
either be omitted, or must be specified completely (long form)
e.g., INSTrument (long form) has the same effect as INST (short form).
• Commands/queries may be given in upper/lower case (long form)
e.g., SoUrCe is allowed.
• Text shown between brackets [] is optional.
e.g., :[SOUR]VOLT:[LEV] TRIG has the same effect as :VOLT TRIG
3.4.8 STATUS REPORTING
The status reporting of the MST 488-27 follows the SCPI and IEEE 488.2 requirements. The
serial poll response of the MST 488-27 provides summary bits of the status and error reporting
system. The simplest status report is the command valid reporting and data availablity, This suc-
cessful decoding of a command string generates no error and is indicated by the bit 3 of the
serial poll response being a zero. The setting of bit 4 in the status byte indicates data is avail-
able to the controller in response a command query message.
3.4.8.1 STATUS REPORTING STRUCTURE
The status reporting of the MST 488-27 uses four status registers, illustrated in Figure 3-4.
These registers are the Questionable, Operation, Standard Event and Service Request regis-
ters. The Questionable and Operation registers are 16 bit registers and the Standard Event and
Service Request registers are 8 bits. These four registers are referred to as condition registers.
Each of the four condition registers is associated with two related registers: an event register
which holds unlatched events reported in realtime by the instrument and is cleared by reading
the register, and an enable register which allows the contents of the event register to be passed
through to set the associated condition register.