Remote Control
LiAM User’s Manual
54
Bit 4
CROWBAR
Bit 3
OVER-TEMPERATURE
Bit 2
AC FAULT
Bit 1
FAULT
Bit 0
MODULE ON
The
set_reg
structure, in order to set the desired behaviour must be interpreted
as follows:
FDB command register (8bit):
Bit Function:
Bit 7
BYPASS COMMAND
Bit 6
ON/OFF
Bit 5
RESET
Bit 4
RAMP
Bit 3…0
don’t care
The “BYPASS COMMAND” bit (bit 7 - i.e. MSB) was especially
implemented in order to use the ‘FDB’ command also as a simple read command: by
setting this bit the power supply ignores all other data contained in the
set_reg
and in
the
i_set
fields, thus replying and giving information on its internal
status_reg
,
i_set
and
i_read
.
Thanks to this feature the power unit can be controlled only with a single
command, thus reducing driver (or EPICS IOC) complexity and maximizing
bandwidth.
Example:
Suppose that the LiAM power supply unit is turned on and it is regulating a 4.5000A
output current (on a
15
Ω resistive value).
The user then sends the following command:
FDB:50:-01.2453
\
r
#FDB:6001:-01.2453:+04.5002
\r
After sending the FDB command, the PS turns on (it was already ON in this
example) and sets its current to -1.2453A reaching this setpoint with a ramp (defined
by the slew rate value stored in the power supply non-volatile memory).
