3 Functional description
Note:
D
o
not activate the RESET button after VMEbus cycles has started on the
backplane. This may cause BgL to be erroneously shown as BgL=O.
BRx*
BGxIN*/OUT*
BBSY*
"BgL"
/ Latched Bus Request ,
Latched Bus Grant Level
AS*
\
:
/ ( D a t a Transfer
Addr/Data
S
i
g
n
a
l
s
)
DTACKVBERR*f
-
-
(Arbitration
signals)
1)
2
)
Bus Grant — > Transaction
Sampling S a m p l i n g
Figure 14. Synchronous (State) sampling of VMEbus, showing the internal
latching of the BR* and BG* signals in the analyzer (dashed lines).
Data cycle sampling
Normally, bus transactions are sampled on the falling edge of DTACK* or
BERR*, conditioned by DS1* or DSO* being low. This will capture all address,
data and control signal information, as well as the stored Bus Level from the
Bus Grant sampling as described above.
IRQ -> IACK
Normally, the active interrupt request signal (IRQx*) on the VME backplane
goes away immediately after IACK* is taken low, too early for being sampled
by the falling edge of DTACK*. To ensure capture of the active interrupt
request line in interrupt acknowledge cycles ("IACK") even during state
sampling, the pending IRQx* may be latched internally until DTACK* goes
low
(actually until IACK* goes high).
This feature can be turned off by the command E d i t / S a m p l i n g
mode/Options/State Sampling o p t i o n s '
(Note: HW ECO level
B6 or higher is required for this feature to be available).
RMW, Block
If a Read-Modify-Write cycle or Block cycle is transferred, this is signalled on
the VMEbus by not taking AS* high between cycles. This will be detected by
special circuitry in the VBT-325, and a separate bit in the trace is set to indicate
30
V
B
T
-
3
2
5
User's Manual
V
M
E
T
R
O
Summary of Contents for VBAT-PB
Page 15: ...x i v 1 1 I 1 1 I I i i I I 1 I I 1 I 1 I I ...
Page 23: ...1VBT 325 Product overview 8 V B T 3 2 5 User s Manual V M E T R O ...
Page 125: ...8 Trace examples 110 V B T 3 2 5 User s Manual V M E T R O ...
Page 144: ...9 VBAT PB VME bus anomaly trigger ITP40 I GND VMETRO V B T 3 2 5 User s Manual 1 2 9 ...
Page 159: ...1 1Jumper settings 144 V B T 3 2 5 User s Manual V M E T R O ...
Page 181: ...16 Simulator for PC 166 V B T 3 2 5 User s Manual V M E T R O ...
