GE Industrial Solutions AF-600 FP Profibus DP User Manual

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2.1.6 Connecting the Network

Proper termination of the network is essential. A mismatch of impedance may
result in reflections on the line that will corrupt data transmission.

The Profibus DP Communications Module has a suitable termina-
tion, activated by switch 1 located on the Profibus option. The
switches must be on to terminate the network. The factory setting
is off.

Nodes at the physical ends of each segment must be terminated.

When power to the Profibus DP Communications Module is down,
please note that the termination is still active, although not func-
tional.

Most masters and repeaters are equipped with their own termina-
tion.

If an external termination circuit consisting of three resistors is con-
nected to the network, a 5V DC power supply must be used. Terminal
66 and 67 can be used for this.

The CS-pin on the Profibus connector is Control Select. When option
goes into active state and sends a message, the CS pin goes high
(+5 Volts). This can be used to control optical transmitters etc. or for
triggering measurement equipment like an oscilloscope.

D-sub 9 connector.
If desired, a D-sub 9 adaptor can be added as an option.
N.B.: If the D-sub 9 adaptor is used, please be aware that the ter-
mination switch on the Profibus option is set to OFF, to avoid double
termination. as the Profibus D-sub 9 connector also features a ter-
mination switch.

Illustration 2.1: 62 = RxD/TxD-P red cable (Siemens B)
63 = RxD/TxD-N green cable (Siemens A)
66 and 67 are for use with external terminator resistor only

AF-650 GP/AF-600 FP Profibus DP Operating Instructions