Philips 6652C - Page 59

HIGH-SPEED DUMP MODE
Every normal. measuring cycle include computation
of the result (e.g. to get frequency). A calcu-
lation of the resolution (number of displayed
digits) as well as display formatting is also
performed. The duration of this computation
phase
is some 10 milliseconds.
This wi 11 limit the measuring speed to 20 ••• 50
readings/sec, even when a minimum measuring
time
(1 ••• 2~s) has been selected.
The use of high speed dump mode is a way to in-
crease measuring speed to 400 •• , 500 readings/
sec. (typical when minimum measuring time is se-
lected). In this mode the microcomputer skips
the computation phase and will just output the
contents of decade count registers. The computa-
tion of the result as well as calculation of re-
solution must then be made by the controller.
The dump mode is entered by programming "HS1".
When High Speed Dump mode has started the dis-
play will indicate "HS" instead of measuring
values. There are four different ways to termi-
nate the dump mode:
Sending programming string
11
HS0".
Sending programming string "0".
Sending bus commands SOC or DCL (device
clear).
Go to local mode .
The dump mode output string contains 24 or 25
ASCII characters, with the following format:
I Code I X [xj ........ Jxl xlol (D) I
byte 1
byte 2 ... 23
byte 24
byte 25
= Alphabetic code A ••• U specifying
what calculation should be made.
= Register contents (numeric).
= Selected delimiter.
= Delimiter lf (only if delimiter
CR + Lf has been selected).
The 22 numeric characters normally represents
the contents of the event count register and
the time count register respectively.
In totalizing mode only event counts are repre-
sented in the numeric string. In single time
measurements only time counts are represented.
The following abbreviations are used:
T = Time count register contents.
E = Event count register contents.
X = Don't care byte.
D = Delimiter.
Individual bytes in the time count and event
count registers are numbered e.g. T9, T5, E11,
E1 etc. Least significant byte is called T1 and
E1 resp. There are 6 different formats depending
on
the measuring function selected. There are as
many as 21 possible ways of calculating the
final result. The calculation algorithm to be
used
is indicated by the code (A ••• U) in byte
No. 1.
format No.
Functions:
PM 6652/54: Period, Phase, Duty factor, Freq A,
Ratio A/B, Time Average, Freq. c.
Output format:
Byte 1 2 3
•• 11 12 13 14 .• 21 22 23 24 (25)
Calculation Code Calculation
algorithms:
c
(T/E)x1o-7
G
(T/E)x360
H
T/E
K
(E/T)x108
L
(E/T)x1o7
0 E/(T+1)
p
(E/Cf+1 ))x1o-7
r
(E/T)x16x108
Format No. 2
Functions:
PM 6654: Freq A, Freq c, Period A, Time Average
PM 6652: -
Output
format:
Byte 1 2 3 12 13 14 2324
(25)
Calculation Code
Calculation
algorithms:
J
( E/T)x5x108
M
(E/T)xBx1Q9
N (T/E)x2x1o-
9
R
(T/E)x10-8
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