CEL-MAR ADA-401WA Kullanıcı Kılavuzu - Sayfa 7
Medya Dönüştürücü CEL-MAR ADA-401WA için çevrimiçi göz atın veya pdf Kullanıcı Kılavuzu indirin. CEL-MAR ADA-401WA 16 sayfaları. Addressable rs-485/rs-422 to 1-wire converter
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ADA-401WA
3.3.1. LINE TERMINATION
The application of Line Termination (terminator) Rt = 120 W (ohms) will reduce electrical reflection in data line at high baud rate. It is
not needed below 9600Bd. The Line Termination resistor should be used if the distance is over 1000m @ 9600Bd or 700m @
19200Bd transmission, the resistor can be necessary if there are problems with the transmission correctness. Example connection of
Rt to screw terminal block of RS485/422 interface ADA-401WA are shown on Fig. 6 & 7.
3.4. CONNECTION TO 1-WIRE NETWORK
3.4.1. CONNECTION 1-WIRE SENSORS
Way to link temperature sensor to ADA-401WA converter is shown on figure below.
ADA-401WA
RS485/422
connector
Tx+/ A
Tx-/ B
Rx+
Rx-
GND
ADA-401WA
RS485/422
connector
Tx+/ A
Tx-/ B
Rx+
Rx-
GND
3.4.2. LIMITATIONS OF 1-WIRE BUS
The maximum length of 1-wire bus as layouts producer can be even 400m and the maximum number of sensors can be 500.
However, when building the bus, remember that, each sensor is a shortening of 0,5 meters and 100 meters of cable causes additional
capacity load data line 5nF increasing signal distortion.
1-WIRE bus length and number of sensors will be less and will depend on:
– used cables,
– topology connection,
– quality implementation of connections,
– interference from external electromagnetic fields.
RECOMMENDS:
– application of twisted cables UTP 4x2x0,5,
– powered converter with an individual power supply with good parameters, eg. DR-15-24,
– linear topology of 1-WIRE bus (sensors in a star topology can be converted to linear topology by using Passive 1-WIRE
Bus Splitter ADA-DNB400),
– finishing 1-WIRE bus by sensor,
– connecting unused wires and screen cable to rail EP of electrical installation.
1-WIRE
connector
GND
1-W
VDD
V +
V -
Power
Supply
V-
V+
10–30 VDC
3W
DS18B20
Sensor
Fig. 8. Sensor connection to ADA-401WA converter by 3-wire 1-WIRE Bus
1-WIRE
connector
GND
1-W
VDD
V +
V -
Power
Supply
V-
V+
10–30 VDC
3W
DS18B20
Sensor
Fig. 9. Sensor connection to ADA-401WA converter by 2-wire 1-WIRE Bus
1-WIRE (3W) Bus
DS18B20
Sensor
1-WIRE (3W) Bus
DS18B20
Sensor
7
DS18B20
Sensor
DS18B20
Sensor