Siemens SIMATIC NET PROFIBUS - Manual (Page 245)

Testing PROFIBUS
A-5
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
A.1.6 How the Unit Functions
Testing Cables
The previously described tests and measurements are based essentially on
various voltage, reflection and resistance measurements. To check the cable, the
test unit is connected to one end of the cable and a test connector at the other.
When installing the cable, the user works gradually from connector to connector. At
the press of a button the measurements are made automatically and the test
results displayed.
Tests on Nodes
When testing on the node itself, a point-to-point link is established between the test
unit and the node. To complete the tests, the accessibility of the attached slaves is
checked on the wired-up bus. The user can have a list of accessible slaves created
automatically or can check the accessibility of a single slave by specifying its
address manually.
Displaying the Test Results
Apart from the actual test result, the display also indicates concrete measures that
can be taken to remedy problems. During the measurement of the reflections, the
location of the problem is also displayed. This means that the user does not
require specialized PROFIBUS knowledge to work with the test unit and to find
typical problems in the wiring and setup and to eliminate them. No additional
devices are necessary for the measurements. This means a drastic reduction in
commissioning times and plant downtimes.
Documenting the System Status
The BT200 simplifies the creation of an acceptance report to document the system
status at the time of acceptance. As standard, the unit is designed for operation on
PROFIBUS cables complying with type A (EN 50170). The unit parameters can,
however, be modified by entering the electrical parameters for the cable to be
tested. This means (whatever cable type is used) that the location of a problem
can be displayed in meters as well as the total length of the installed cable.
Battery Operation
The device has an accumulator battery. This ensures that the user can test the
entire system regardless of the network. The unit is turned off automatically after 3
minutes if no input is made ensuring that the battery has a long working life and
saving power.