Casella CEL CEL-414 - Manual (Page 39)

If an external filter set is fitted, pin 4 of
the socket on the bottom of the filter
gives filtered AC. Both outputs have a
maximum level of 7.75 V RMS (8.0 V
RMS on the CEL-493/3). Refer to Sec-
tions 3.5 and 3.6, and Chapter 11 for pre-
cise details of the input and output
possibilities.
When the CEL-160 Graphic Recorder is
used together with the CEL-278/3 or /2
Octave Filter Set, or the CEL-296/3 or /2
Octave/Third Octave Autoscan Filter Set,
centre frequencies can be switched by
the recorder to produce fully annotated
spectrograms automatically.
A standard C4416/2 (2 m) Cable connects
the CEL-160 to the sound level meter, or
filter set auxiliary socket as shown in Fig-
ure 18 for AC signals only. C4534/2 Cable
(2 m) is required if CEL-296/3 and /2
autoscanning are required.
The CEL low power digital interface is a
standard feature on all “B” & “D” ver-
sions and on the CEL-493/3. It can also
be retro-fitted on any “A” or “C” version
that does not have built in octave filters
(except for the CEL-414/3). Please con-
sult your CEL Agent or CEL at Hitchin for
details.
The interface is a serial data stream basi-
cally similar to the RS 232C. However,
modifications have been made to reduce
the amount of data handled and minimise
the power consumption.
It is designed for direct connection to the
CEL-238A, CEL338, and CEL-438 Digital
Recorders/Analysers, which can produce
hard copies of results, and allow further
data reduction to be performed (as de-
scribed in Section 7.3).
The CEL-433 Serial Interface facilitates
connection with other computer systems
by providing an output at RS 232 levels
with a transmission rate of 4800 baud.
A digital output is available for the parame-
ter currently selected on the digital dis-
play, and this will be updated every 500
milliseconds. Remote control of the func-
tion select and reset lines enable the full
range of results to be produced via the in-
terface. Results are transmitted in 5 byte
data packages as follows.
Byte 1
This contains information on which fre-
quency weighting and parameter have
been selected.
The CEL-493/3 and B version format is as
follows:
BIT 7 6 5 4 3 2 1 Ø
1 W Ø Ø F F F F
920008
CEL-160
C4416/2 or C4534/2
Figure 18: Connection with
CEL-160 Graphic Level Recorder
8. DIGITAL INTERFACE (B & D, and CEL-493/3 only)
General CEL Sound Level Meters Handbook - Page 35