Racal Instruments 9916 - Page 83

The maximum overshoot that will. occur is given by~-
-3
Counting Rote x 4 x la counts.
It is advisable to use the Print Command as a Idota valid' si.gnal In such systems.
Frequency Meters - Special Applications
17. In some applications it is not possible to use the interface in the manner described in
Para
12. For example, in control systems, where the output of the interface is used
as
feedback to the device on the input of the counter, problems arise because the next gate
time has already started before the information becomes available from the previous one.
Therefore, even if the feedback correction is made almost instantly, the reading at the end
of the next gate time will be incorrect. Altematively, if the correction process takes more
than one gate time, the end of gate time immediately following the process will also give
incorrect results. These problems may be overcome by applying a Hold signal to the Print
Hold
input (pin 49) for the length of time that the correction takes, plus an additional time
. <f) ensure that the gate time from which the next data is to be token cannot start until the
~orrection process has been completed, as shown in Fig, A3,
GATE
CORRECTION liME
PRIN r CO ...... ANO
r:;l\m< ( 111111m, ~!~ Irn, NEXT VALID 1
1
~ ~ I GATE TU".
I I
1 I
1 1
I I
f--I-lm< ~ : I
I ~ I rn, 'IL -'--- ---i
l
I I
Ol.T A UPOAIE ---J I;r------;r-----------+.I _-..J
I
I
I
Q :
I'~; 'I I 1
---- '---------'-1-----1/ I
I I \
I .: 1
r--------i-! -----./ ~ ~: +1 _
1 I
1 I
I I
;-1 /~!----.....:~--I I
r;;oSsE;:j 71 r;:o;r :;i:;:J
PR-1Nl HOLD INPur
Fig.A3
Section 4 99 Series Appendix 1.
Page App. 6.