Bus Termination - GE VersaPoint IC220PBI002 User Manual

4

Bus Termination

Termination resistors are needed, as defined in DIN 19245 Part 1 section 3.1.2.5.
One terminator must be applied at each end of a network segment.
M aster
Generally, termination is provided in commercially-available Profibus standard
network connectors. Some connector vendors provide termination capability in
the connector and a switch on the connector to enable/disable termination. Some
connector vendors provide both terminated and unterminated connectors.
Important: For proper network termination, it is essential that the terminating
devices maintain power. Power is provided by the device on Pin 6 and Ground on
Pin 5. If power is lost to either terminating device, the network may not operate
correctly. Generally, the lone network master device is one of the terminating
devices. Therefore, a loss of power to the network master renders the network
inoperable anyway. The other terminating device may be a critical slave device
which must maintain power or a separately powered, stand-alone terminator.
These stand-alone devices are commercially available.
4-16 VersaPoint™ I/O System Profibus-DP NIU User's Manual – August 2005
Master Slave
Slave S lave
T erm ination R equired
(Segm ent 1)
VP (6)
RxD/TxD-P (3)
RxD/TxD-N (8)
DGND (5)
Slave Slave Slave
Termination Required
(Segment 1)
R epeater
Slave
Term ination R equired
(Segm ent 2)
Ru = 390 Ohms
Rt = 220 Ohms
Rd = 390 Ohms
Slave
Slave S lave
GFK-1911B