Fluke 225C User Manual - Page 158

RS-232 Bus., AA-11

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RS-232 Bus. RS-232 allows two-way communication between a controller and a device such as modem, printer, or sensor. Per device a dedicated link is needed. Initially the RS-232 definition offered an extensive handshake protocol with separate handshake lines (hardware handshake); later software handshake allowed data exchange via only 2 lines (plus ground). Data rates may be low, depending on the application. To check this bustype, 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 A Appendices Bushealth Measurements The figure below shows a Female DB-9 connector wired for hardware handshake. Lines used for software handshake are indicated with black dots. In case there are handshake lines, they each can be checked individually because all use the same voltage levels. A-11

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Appendices
Bushealth Measurements
A
A-11
RS-232 Bus.
RS-232 allows two-way communication between a
controller and a device such as modem, printer, or
sensor. Per device a dedicated link is needed. Initially the
RS-232 definition offered an extensive handshake
protocol with separate handshake lines (hardware
handshake); later software handshake allowed data
exchange via only 2 lines (plus ground). Data rates may
be low, depending on the application.
To check this bustype, 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 each can be
checked individually because all use the same voltage
levels.
The figure below shows a Female DB-9 connector wired
for hardware handshake. Lines used for software
handshake are indicated with black dots.