DTU2xx Data Logger Series
User Guide. r. 2.1 | 2021-11-10
Tel.: +420 538 890 720
13
e-mail: [email protected]
The sensor is powered from an external power supply source. Such a scheme is used if the
supply voltage at the DTU outputs (
7.5V
and
12V
) does not correspond to the voltage that
must be supplied to the sensor.
In this case, the sensor is connected according to the diagram below. 4-20mA output is
connected to any of the inputs
IO1-IO4
of the DTU, the
+Upow
contact of the sensor is
connected to the
+Upow
of the power supply, and the
–Upow
of the PSU is connected
to any contact
G
of the data logger.
RS-232 and RS-485 Interfaces
RS-232 and RS-485 interfaces are designed for remote data collection
from devices. DTU allows organizing a transparent communication
channel between serial devices and upper-level software even in cases
where there is no external power supply at the facility, since the device
can operate autonomously, from a 3500 mAh battery.
The interfaces are co-located, so all information received over a
transparent TCP channel goes to both serial ports, and the response
received over any of the interfaces is transmitted into a single
transparent TCP channel. At one point in time, data exchange is possible
between one of the interfaces ("Client") and a remote node ("Server").
The RS-232 interface
uses three signals
: Rx, Tx, G
.
The RS-485 interface supports
A (+)
and
B (-)
signals, and also has a
built-in 120Ω
(T)
terminal resistor output that is connected to the line
when shorted to
B (-).
The load capacity of the RS-485 interface allows you to simultaneously connect:
up to 32 devices with a single load (1UL);
up to 64 devices with 1/2-unit load (1 / 2UL);
up to 128 devices with 1/4-unit load (1 / 4UL);
up to 256 devices with 1/8-unit load (1 / 8UL).
Fig. 9. Connecting the current sensor to the DTU
(powered by an external power supply unit).
Fig. 10. RS-232 and RS-485 ports.
