Conel CDA 70 User Manual - page 37
CIO
DESCRIPTION
37
3.3.3.
Measuring DSR output signal level
On CDA70 side, DSR signals on individual user interfaces are output signals. They are
not internally controlled. Individual signals are connected via 1k8 ohms resistors to the 12V
supply voltage (the same voltage as at the supply connector of CDA70).
Due to the loading of DSR output by a 100 ohm resistor to the earth, the supply voltage
on the output drops to 2V. CDA70 recognises the connection of the service cable and initiates
the communication on this user interface using the ARNEP protocol with defined
communication parameters. It is forbidden for user applications to load the output so that
the voltage would drop below 3V. The signal can be used for user applications within
the range of 3V to 12V.
As well as the other signals, DSR values are accessible within CIO communication
reports (see the ARNEP protocol description).
3.4. Output signal for disconnection of supply voltage
The only exclusively "output" signal is PWRSV (Power Save). The signal is linked to
the supply connector (see the supply connector description). It is connected as universal I/O
signal outputs. This is an open collector that switches PWRSV signal to the ground (GND).
The output is controlled by a report, similarly to I/O outputs.
3.5. Technical parameters
Number of I/O signals on I/O port
5
Basic range of the analogue input supply voltage
0 to 5V
Maximum switched current of binary output
500 mA
Maximum switched voltage of binary output
30 V
3.6. Connecting CIO signals to user device
It is not appropriate and often even possible to connect I/O interface signals directly to
the user device. To measure current, resistance, broader ranges of voltage, it is necessary to
insert electronic circuits, which adjust the measured quantities to voltage ranging from 0 to 5V
and also protect inputs against disturbing influences and dangerous overvoltage. Moreover, it
is also necessary to insert electronic circuits for operating the power parts of the user interface
because a transistor with the open collector is able to switch current up to 500mA and voltage
up to 20V.
Two additional CIO modules, which form an interface between a user's device and I/O
signals, are created for the practical use of I/O signals
Name
Type
Description
CIO ANI 2
Analogue
input
Analogue differential input for small voltage, current and resistance
measuring. It includes differential amplifier with adjustable power 1 to
10000. Exact current source 0.1 to 3 mA can be used to measure
resistance. Configuration of the input signals, amplification and
current source is carried out through resistance net. Presence of the
input signal relevant to A/D converter working range is signalled by