HP 6038A Service Manual

3-81 A service request can also be generated at power on
(PON), depending on the setting of the rear-panei PON SRQ
switch. Therefore, with PON SRQ enabled, if a momentary
power dropout causes the power supply memory to lose its pro¬
grammed values, PON alerts the operator that the power supply
has been initialized (see Paragraph 3-100).
3-82 If the power supply fails self test at power on it will
not respond to serial poll or any other commands on HP-IB.
The user should include a time-out In his program after which
the controller will not wait for the power supply to respond.
If the time-out occurs, the power supply can be assumed to
be malfunctioning and should be removed for service.
3-83 The SRQ indicator turns on whenever the power sup¬
ply Is requesting service from the controller, and remains on
until the controller conducts a serial poll. Serial poll resets the
SRQ bit and turns off the SRQ indicator, regardless of whether
the fault that caused service request continues to exist.
3-84 Serial Poll. In a serial poll the controller polls each
device on the bus, one at a time. The power supply responds
by placing the contents of the eight-bit serial poll register on
the HP-IB data lines. Table 3-5 defines each of the bits in the
serial poll register and defines what causes each bit to be set
and reset. Bit positions 0 through 7 are placed on DIO lines 1
through 8. Note that the serial poll register represents only the
power supply connected to the HP-IB, not other power sup¬
plies that may be slaved to the HP-IB connected unit.
3-85 Parallel Poll. Parallel poll allows the controller to
receive one bit of data from each of many or all instruments
on the bus at the same time. In Hewlett-Packard power sup¬
plies this bit corresponds to bit 6, the RQS bit, of the serial poll
register. Because the controller can receive this bit from at least
eight instruments at one time, the controller can determine
quickly which of a number of Instruments on the bus requested
service. The controller can then query that instrument to deter¬
mine the cause of the service request. Parallel poll does not
reset the service request bit in the power supply. The power
supply's response to parallel poll can be configured remotely
from the controller, or it can be configured locally.
NOTE
IEEE-438 does not define what data an instru¬
ment should put on the bus in response to
parallel poll. Many instruments, such as
Hewlett-Packard power supplies, indicate the
state of their RQS bit, but the operator should
not assume that all instruments on the bus
respond to parallel poll with their RQS bit.
Table 3-5. Serial Poll Register
Bit Position
7 6 5
4 3 2 1 0
Bit Weight
128 64
32 16 8 4 2 1
Condition -
RQS
ERR RDY
- -
PON FAU
RQS Requesting Service
ERR Remote Programming Error
RDY Ready to Process Commands
PON Power On Reset
FAD Fault Condition
RQS is set when power supply generates a service request, and is reset Immediately after a serial poll is conducted.
ERR follows ERR bit in Status Register, which is set whenever power supply detects a remote programming error.
ERR is reset by ERR? query.
RDY is set whenever power supply finishes processing a command, and is reset when power supply starts to process
a new command. Note that power supply input buffer can accept new commands via HP-IB even white unit is busy
processing previously received commands.
PON is set when ac input power is turned on and is reset by CLR command or Device Clear interface message. PON
is set in serial poll register regardless of whether PON SRQ Is enabled by rear-pane! switch.
FAU is set when any bit is set in Fault Register and is reset by FAULT? query.
3-12

HP 6038A Specifications

General

Brand	HP
Model	6038A
Category	Inverter
Language	English