AMETEK BPS Series Programming Manual - Manual (Page 16)

AMETEK Programmable Power BPS / MX / RS Series SCPI Programming Manual
16 Manual P/N 7003-961 Rev AA
If you enter SOURCe the active header path moves one colon to the right. The interface is
now ready to accept :VOLTage :FREQuency, or :CURRent as the next header. You must
include the colon, because it is required between headers.
If you now enter :VOLTage, the active path again moves one colon to the right. The interface
is now ready to accept either :RANGe or :LEVel as the next header.
If you now enter :RANGe you have reached the end of the command string. The active
header path remains at :RANGe If you wished, you could have entered :RANGe 135 ;LEVel
115 and it would be accepted as a compound message consisting of:
SOURce:VOLTage:RANGe 150.
SOURce:VOLTage:LEVel 115.
The entire message would be:
SOURce:VOLTage:RANGe 150;LEVel 115
The message terminator after LEVel 115 returns the path to the root.
The Effect of Optional Headers
If a command includes optional headers, the interface assumes they are there. For example,
if you enter [SOURCe]:VOLTage 115, the interface recognizes it as
[SOURce]:VOLTage:LEVel 115. This returns the active path to the root (:VOLTage). But if
you enter [SOURce]:VOLTage:LEVel 115 then the active path remains at :LEVel This allows
you to send
[SOURce]:VOLTage:LEVel 115;RANGe 150
in one message. If you did not send LEVel you are allowed to send the following command:
[SOURce]:VOLTage 115;FREQuency 60
The optional header [SOURce] precedes the current, frequency, function, phase, pulse, list,
and voltage subsystems. This effectively makes :CURRent,:FREQuency, :FUNCtion,
:PHASe, :PULse, :LIST, and :VOLTage root-level commands.
Moving Among Subsystems
In order to combine commands from different subsystems, you need to be able to restore
the active path to the root. You do this with the root specifier (:). For example, you could
open the output relay and check the status of the Operation Condition register as follows:
OUTPut:STATe ON
STATus:OPERation:CONDition?
Because the root specifier resets the command parser to the root, you can use the root
specifier and do the same thing in one message:
OUTPut on; :STATus:OPERation:CONDition?
The following message shows how to combine commands from different subsystems as well
as within the same subsystem:
VOLTage:RANGe 150;LEVel 115;:CURRent 10;PROTection:STATe ON
Note the use of the optional header LEVel to maintain the correct path within the voltage and
current subsystems and the use of the root specifier to move between subsytems. The
"Enhanced Tree Walking Implementation" given in appendix A of the IEEE 488.2 standard is
not implemented in the AC/DC source.