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6 .4
STACK DATA FORMAT
When the Bus Monitor is commanded to start, all messages will be stored before the trigger condition is met.
Therefore, all pre-trigger data is captured. The first captured message will start at the address defined by the Start
Page Register. All following messages will start on an even PAGE boundary. The STACK data will wraparound
after the Finish Page Register value has been exceeded. The format of the messages are shown in table 6-4.
Table 6-4
Stack Data Format
WORD No.
NAME
1
2
3
4
5
:
N-4
N-3
N-2
N-1
N
Previous Address Pointer
Time Stamp HI
Time Stamp LO
Data
Errors
:
Data
Errors
RT Response Time 1 (LSB = 0.5 uS)
RT Response Time 2 (LSB = 0.5 uS)
Next Address Pointer
.
6 .4 .1
Previous Address Pointer
The first word of each message will define the page address of the previous message.
The first message stored will set this pointer to 0000H.
6 .4 .2
Time Stamp HI/LO
These two locations are a 32 bit word defining the value of the 32 bit 0.5µS clock when the message started.
6 .4 .3
Da t a
These words describe the previous DATA word TYPE, BUS_ID and associated errors as follows:
D15
ED
D14
0
ED
Py
Mn
Lg
Sh
=1
=1
=1
=1
=1
U
U
M
R
C
UM
M 111111000666111 R
Reeevvv C
C
D13
0
D12
Py
D11
Mn
D10
Lg
D09
Sh
D08
T1
D07
T0
D06
WC
Indicates last 1553B word in message.
1553B data word had a Parity error.
1553B data word had a Manchester error.
1553B data word had too many bits (Long).
1553B data word had too few bits (Short).
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D05
B1
D04
B0
D03
NR
D02
TA
D01
Sy
D00
0