GHM DeltaOhm HD402 Series, Руководство по эксплуатации

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HD402…
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V1.1
3.1 E
LECTRICAL CONNECTIONS
Active current analog output Voltage analog output
2-wire current analog output Relay output
In the models with relay output, at power on, the alarm LED blinks quickly while the in-
strument information is displayed.
RS485 connection
In the RS485 connection, the instruments are connected in a sequence through a
shielded cable with twisted pair for signals and a third wire for the common. Line ter-
mination must be set at the two network ends.
The maximum number of devices that can be connected to the RS485 line (Bus) de-
pends on the load characteristics of the devices to be connected. The RS485 standard
requires that the total load does not exceed 32 unit loads. The load of an HD402ST…
transmitter is equal to ¼ of unit load. If the total load is greater than 32 unit loads, di-
vide the network into segments and add a signal repeater between a segment and the
successive one. Line termination should be applied at both ends of each segment.
The instrument has a built-in line termination that can be connected or removed
through a short jumper placed next to the terminal block. If the instrument is the last
or the first device of a network group, connect the termination placing the short
jumper between the “RT” and “120 ohm” indications. If the instrument is not at the
Power supply Power supply
Power supply
Power supply
Other sensors with
RS485 output
Termination
Termination
PLC, data logger or
RS485/USB or RS485/RS232
converter for PC
Power supply