Philips 6652C - Service Request

SERVICE REQUEST
A Service Request (SRQ) is sent from the counter
to the controller in the following cases:
When service request is disabled (SQ~)
- On programming errorst such as false codes;
measuring time
out of range; trigger levels
out of range etc.
After the execution of any of the tests
TS1 ••• T56 and a test error is found.
When service request is enabled (SQ1)
- When a measuring result. is ready for output.
Any of the tests fS1 ••• TS6 is finished.
When limit monitoring is enabled (SQ2; SQ3)
When the measuring result is outside (inside)
the set limits.
Monitoring of alarm limits
The limit monitoring in a PM66S2/54 may be per-
formed in four different ways. An SRQ-alarm is
given in the following cases:
If the value(X) is outside the range a ••• b
(X< at X > b). "SQ2" must be programmed.
If the value (X) is inside the range a ... b
(a < X < b) • "SQ3" must be programmed.
If the value (X) is below the limit c (X < c)
"SQ2" and "SK1" must be programmed.
If the value (X) is above the limit c (X > c)
"SQJ" and "SK1" must be programmed.
In all the above cases a prerequisit is that
the MATH function is enabled ("ME1"). The range
a ••• b is set by using the MATH. constants K and
L
to appropriate values. If an SRO-alarm is to
be given for measuring values (X) outside the
range a ••• b, then K and L should be selected:
1 a
K =
L =
b - a
b- a
For example: The counter must monitor a frequen-
cy
with a nominal value of 455kHz. The counter
should not send anything on the bus as long as
the frequency falls inside the range
4 SO •• • 460kHz.
When the measured frequency falls outside that
range; a SRQ is sent t.o the controller.
a : 450 X 103 b : 460 X 10J
The constants K and L should be selected as:
1
450x1o3
K =
=---: 10-4 L :
---= -45
b-a 10x103
The counter should be programmed as follows:
1. Set K = 10-4
("SK1E-4")
2. Set L = -45 ("SL-45")
3.· Enable Math ("ME1 ")
4. Activate alarm Monitoring
("SQ2")
There is a spec ial case: When K is set to 1, the
counter monitors whether the measured value (X)
is above or below a limit value (c). To get a
SRO-alarm if X > c then K and L have to be
selected as:
K : 1
L = - C
Example: An SRQ should be sent. when a time
interval measurement results in a value higher
than 400ms. In this case K = 1 and L = - 0.4.
fhe counter should be programmed as follows:
1 •
Set K = 1
("SK1")
2.
Set L : -0.4
("SL-0.4")
3. Enable Math
("ME1")
4. Activate Alarm monitoring
("503")
Limit monitoring is illustrated below:
Alarm when outside
range
Alarm when inside
range
b
"502", K::;t1
Alarm when below
limit
"SQ2",
K =
a
c
"SQ3", K ::;t 1
Alarm when above
limit
"SQ3", K = 1
Fig.
5.3 Limit monitoring.
b
a
c
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