Series PC Manual V 1.0 - Rev. 3
– 03/01/01
DS Europe
13
9.2. ABSORBED CURRENT
The absorbed current is about 70 mA (typical), with two cursors, analog output of 0÷10 V
and active serial connection.
With the two current analog outputs, the absorbed current is about 110 mA.
In the version used for level measuring “L”, the absorbed current is about 30 mA.
9.3. SAMPLING FREQUENCY
The maximum sampling frequency is 1 kHz for transducers with strokes of up to 350 mm.
The sampling frequency is strictly related to:
•
Transducer stroke.
•
Number of cursors used: if a cursor gives the availability of a sampling frequency
equivalent to 1 kHz, when using two cursors, each cursor will be sampled at a
frequency equivalent to 500 Hz.
•
Analog output for cursor velocity.
Version for level measurements “L” have a 7Hz sampling frequency.
To calculate the possible sampling frequencies consult
Table 1.
TRANSDUCER STROKES
SAMPLING FREQUENCY
Up to 350 mm
1 KHz
from 350 to 1500 mm
500 Hz
from 1500 to 3000 mm
250 Hz
Table 1
: maximum sampling frequency with respect to length.
Whenever a
remote computer
should request, by means of RS 485 connection (57.600
baud), the Cursor 0 position measurement, will have:
Request from remote computer
:
@ 0 R 0 <CR>, for a total of 5 characters transmitted
Transducer reply
:
0 R 0 1 2 0 5 0 0 <CR>, for a total of 10 characters transmitted
A program that continually questions the transducer, will generate (between questions and
replies) a traffic of 15 characters. To transmit one character we need: 1
start
bit, 8
data
bits
and 1 stop bit, thus a total of 10 bits per character.
So, considering requests and replies the total required bits amount to 150.
At transmission velocity of 57.600 bit/second, we obtain:
57.600 bit/ second
------------------------------ = 384 measurements/second (maximum)
150 bit
The computer may request two cursors to be measured. In this case the maximum number
of measurement obtainable per second will be halved. Remember that these performance
rates strictly depend on the computer (operating system and hardware) and the program
structure used to interrogate the transducer.
For additional informations about serial communications protocol refer to Chapter 13.
