Philips 6652C - Status Byte

STATUS BYTE
The status byte is a one byte status message
that is sent from the counter to the controller
as a response to a serial poll. The following
format is used:
Bit B: Always
0.
Bit 7: Service request has been sent (1) or
not (~).
Bit 6: Alarm condition (1) or not (~) .
Bit 5: Counter
is busy (1) or ready (0).
Bit 1-4: Counter status specification.
Service request (bit 7)
Is sent on the following conditions:
If there is a programming error ,
- After each measurement or test if "SQ1" is
programmed.
-
When set alarm limits are passed if "SQ2"
or "SQ3" is programmed.
After self-test errors.
Alarm (bit 6)
Alarm status occurs if:
- The counter is wrongly programmed.
- Set alarm limits are passed.
- Self-test errors.
Busy/ready (bit 5)
The counter is busy during the actual measure-
ment and also during the preparation for the
measurement. The counter is ready when the re-
sult is ready for output on the bus.
Normal measuring cycle
A normal measurement cycle consists of the fol-
lowing phases:
Preparation for measurement.
- Waiting for a trigger command via the bus if
"TE1" is programmed.
-
Waiting for input signal synchronization to
start.
- Measuring.
- Waiting for input signal synchronization to
stop.
Processing the counting register data.
Output of the result.
The normal measuring cycle is illustrated below,
fig. s.s.
IJA IT FOR
INPUT SYNC.
(STOP)
Fig. 5.5 Normal measuring cycle. (The numbers
refer to status byte contents).
The status byte codes for the above phases are
shown in Table 5.5. Note that the preparation
phase can have two different codes depending on
whether repetitive measurements (code TE~) t or
single measurements (trigged mode TE1) have been
selected.
Status message
Preparation (TE0)
Preparation {TE1)
Binary
00010010
00010001
Waiting for trigger TE1 00010011
Waiting for start sync. 00010100
Measuring 00011100
Waiting for stop sync. 00011000
Computing 00010000
Ready for output 00000000
Ready, with service req 01000000
limit alarm " 01100000
Table 5.5
Decimal
18
17
19
20 Husy
2B
24
16
6~ I Ready
96
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