Racal Instruments 9916 Workshop Manual page 78

SERIAL TO PARALLEL
II~TERFACE
UNIT
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INTRODUCTION
1. The interface comprises a metal box, measuring approximately 132 x 95 x 36mm
containi ng the p. c. b assembly 19-0851. Connections are made to printer or data
display via a 50-way fixed socket and to the 199
1
instrument via a frying lead fitted with
a 28-way edge connector. The unit is desi gned to operate wi th the fo! Iowi ng Raca I
counters, referred to in rhis description as the '99' series'
Frequency Meters
Universal Counter Ti mers ( UCT)
~
9910
9911 9900
9901
9912
9913 9902 9903
9914
9915 9904
9905
9916
9917
9906
9917A
9919
9908
2. Definition of Terms
( 1)
( 2)
( 3)
(4)
(5)
FUNCTION
Hold Signal: a signal returned by the users equipment to the interface for
control purposes.
Print Command: a signal output by the interface to indicate that new
measurement information is available.
Print Hold input: An input which allows the user's Hold Signal to prevent
the parallel information from changing.
Hold/Reset input: An input which allows the user1s signal ro prevent the
parallel information from changing and whi ch resets the instrument
when the Hold Signal returns to its normal state, thus starting a new
measurement.
Hold Control: An input to the interface which detern:ines the mode of
operation.
3. The function of the Interface Unit is to'convert the serial b.c.d. data output from
a 199 series' counter to a static.parallel form, suitable for driving a printer, data
di spl ay or processi ng equi pment.
Secti on 4 : 99 Seri es. Appendi xl. Page App. 1.