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TABLE 3-3.
COMMANDS (CONT'D)
Command
Definition/Function
Tags 34,35,.36,
37
Write Test
Check Tag 38
Write Test
(Tag 3A)
Tag' 3D
Tag' 3C
Return To
Track Center-
line (!'tTC)
Tag 3D
Read Header
(ROB)
Tag 3E
Detailed Status
Byte
8
(DSB8)
Tag 3F
3-40
These tag's are recoqnized and replied to by the drive but initiate
no drive operations.
1. A test and diagnostic command requiring prior acceptance of a
Tag
lP.
2. Issued after Write Test (Tag 3A).
If
NRZ
fault occurred (error
condition), bit
20
of bidirectional data lines will be true.
If Current fault occurred (normal condition Write· Test), bit
21 will be true.
Error conditions are cleared when command
drops.
1.
A test and diaqnostic command requiring prior acceptance of a
Tag
lP.
2. Causes drive to write special pattern transferred via bidirec-
tional data lines.
It then checks the following:
•
Toqgling of
NRZ
data as it leaves the Serdes Shift Register.
I~
toggles are absent for more
than 800
nsee
NRZ
fault sets
(refer
to
Write Test Check Tag 38).
•
~e
AC
Write Fault Detector is checked when the controller
raises
the
Da~
modifier line causing a period without byte
transitions.
This should set Write Test Current Fault.
This tag' is recognized and replied to by the drive but initiates no
drive operation.
Invalid command.
1.
A control commande
2. Causes positioner to return to track centerline by resetting
either Shaft Positioner Out (Tag
18)
or Shift Positioner In
(Tag
19).
3. This causes a
10 ms
Positioner Busy status followed by Device
Event Notification
{riEN).
1.
An
input information command.
2. Some function as Read (Tag 25) except that the drive searches
for and must find the address mark before any data transfer can
occur (see discussion on read operations).
This command is recognized and replied to by the drive but ini-
tiates no drive functions.
83318200
A
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