Fluke 225C User Manual - Page 159
RS-485 Bus., Modbus IEA-485/-RS-485
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Fluke 19xC-2x5C Users Manual RS-485 Bus. The RS-485 definition specifies differential (balanced) data lines that are referenced to a ground level. Because of this, noise immunity is better than for RS-232. The impedance between the lines is 120 Ω. RS-485 allows for multiple transmitters and receivers to be connected to the same bus. Data transmission is adressed to a dedicated receiver. Data traffic is not continuous. To check this bustype, ScopeMeter Channel A and B are on and DC coupled. The recommended probes are the Fluke 10:1 probes. Connect the probes as shown below. DATA + DATA DATA GND RS-485 bus system layout is shown in the figure below. CONTROLLER DATA + DATA GND DEVICE 1 DEVICE 2 Modbus IEA-485/-RS-485 A-12
Fluke 19xC-2x5C
Users Manual
A-12
RS-485 Bus.
The RS-485 definition specifies differential (balanced)
data lines that are referenced to a ground level. Because
of this, noise immunity is better than for RS-232. The
impedance between the lines is 120
Ω
. RS-485 allows for
multiple transmitters and receivers to be connected to the
same bus. Data transmission is adressed to a dedicated
receiver. Data traffic is not continuous.
To check this bustype, ScopeMeter Channel A and B are
on and DC coupled. The recommended probes are the
Fluke 10:1 probes. Connect the probes as shown below.
DATA +
DATA -
DATA GND
RS-485 bus system layout is shown in the figure below.
CONTROLLER
DEVICE 1
DEVICE 2
DATA +
DATA -
GND
Modbus IEA-485/-RS-485