Spectra-Physics Tsunami - General Comments on the SCPI Standard Protocol

Lok-to-Clock Electronics
8-17
General comments on the SCPI Standard Protocol
a. Commands are always terminated by an ASCII line feed character
(Indicated by <LF>.)
b. Commands may be combined if separated by semicolons. Com-
mands which branch from the same tree level need not repeat the
headers leading to that level.
c. Parameter and return values for the status registers are spelled out
in ASCII, not sent as single characters. For example, if the only
non-zero bit in the status register is bit 1, then *STB command
returns the ASCII character “2” (hex value 0x32, binary 0010). To
set all bits in a mask register to one, use a parameter value of 255.
Examples:
:SOURce—optionally precedes the commands which branch out below it.
For example,
SOUR:LOOP 1
and
LOOP 1
are equivalent.
:LOOP <parameter>—turns the locking loop off (if the parameter is zero)
or on (if the parameter is non-zero). The following sequence occurs when
the loop is turned on:
a. The system enters the “acquisition mode” where the coarse cavity
length control (motor mike) is used to bring the laser repetition rate
to within the range of the fine length control (the PZT). During this
phase, the “acquisition” and “loop on” bits of the status byte are
set.
:LDLY? *WAI
:FREQ
:UP
:DN
DLY 100<
LF> sets the delay to 100
DLY 100;DLY?<
LF> sets the delay to 100, then reads the set
value
LMON:AC?;DC?<
LF> reads the AC and DC components of the
loop monitor
LMON:AC?;:PZT:AC?<
LF> reads the AC value of the loop monitor,
then the AC value of the PZT monitor.
*ESE 255<
LF> sets all bits in the Event Status Enable reg-
ister to one
Table 8-1: The SCPI Command Set