Appendices
Bushealth Measurements
A
A-5
Modbus IEA-232/RS-232.
Is in use in Process Industry, Building and Factory
Automation. Modbus RS-232 is used for point-to-point
communication. System layout is shown in the figure
below. Continuous data traffic is not ensured.
CONTROLLER
DEVICE UNDER
CONTROL
TxD
RxD
GND
Modbus IEA-232/-RS-232
To check this type of bus, ScopeMeter Channel A is on
and DC coupled. The recommended probe is the Fluke
10:1 probe. Connect the probe as shown below.
TxD or RxD
GND
In case there are handshake lines, they can be measured
as well as far as V-Levels are concerned.
Modbus IEA-485/RS-485.
Is in use in Process Industry, Building and Factory
Automation. Modbus System layout is shown in the figure
below. Continuous data traffic is not ensured.
CONTROLLER
DEVICE 1
DEVICE 2
DATA +
DATA -
GND
Modbus IEA-485/-RS-485
To check this type of bus, ScopeMeter Channel A and B
are on and DC coupled. The recommended probes are
Fluke 10:1 probes.
Connect the probes as shown below.
DATA +
DATA -
DATA GND
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