Rockwell Automation 6008-SV2R VMEbus remote I/O Scanner - Manual (Page 56)

Chapter
Operating in SVĆCompatible Mode
5
5Ć5
Operating Status Byte
The operating status byte holds scanner status information for the VME
master processor. The scanner updates this byte every time it completes
either a block-transfer or a command. The master processor can clear bits
4 and 7; the remaining bits are read only. The structure is as follows:
Figure 5.2
Structure of the operating status byte
7 6 5 4 3 2 1 0
These
bits:
Considerations: These
bits:
Considerations:
bits 0-2 These bits specify the programming mode of the scanner.
These bits are mutually exclusive - the scanner can be in only
one of these modes.
bits 5 If bit 5 is set, the scanner has at least one blockĆtransfer
request in its internal queue. When the queue is empty, the
scanner clears the bit.
bit 3 If the debug mode bit is set by the scanner, the scanner cannot
be shutdown by the internal watchdog.
ATTENTION: Unwanted machine motion can result from
disabling the VME master processor watchdog. Only use the
debug mode when you are debugging the application program
for the VME master processor.
bit 6 If bit 6 is set, at least one adapter has faulted, lost power, or
has been dropped from the I/O link. The VME master
processor can issue the LINK STATUS command for fault
details. When all the adapters in the scan list are cleared of
faults or have been brought back on line, the scanner will clear
this bit.
bit 4 The scanner sets bit 4 when it detects an unsolicited
blockĆtransfer. An unsolicited blockĆtransfer results if a VME
master processor accidentally writes discrete information to an
output image table byte that is mapped to an I/O slot requiring
a block transfer.
When this bit is set, take action to correct this situation because
it can seriously degrade scanner response time. The scanner
can only set this bit; the VME master processor must clear it.
bit 7 If bit 7 is set, an adapter's operating status has changed. The
scanner uses this bit to tell VME master processors of a
change in status of one of the adapters on the I/O link. An
example is that if an operator temporarily pulled the swing arm
from an adapter, the scanner would lose communications with
that adapter. Maybe the operator could quickly put it back and
the status LED and the adapter fault bit (bit 6) would say
everything is working properly, but the adapter fault change bit
would be left set, indicating that an adapter was temporarily off
line. A VME master processor can issue the LINK STATUS
command to make sure the I/O link and all adapters are
operating properly upon seeing this bit set. Only the scanner
can set this bit. The VME master processor must clear it.