Siemens ADVANCE NETWORK COMMUNICATIONS BOARD/DATANET 20005 User Manual download pdf (Page 57)

ANCB Description, Continued

Jumper J2 Settings

The ANCB provides a set of impedance matching jumpers to simplify the

cable interfacing process. Jumper J2 is a six-position header used to

select the proper cable impedance matching circuit for each ANCB

DataNET port. Jumper J2 is logically partitioned into two groups of three

positions, see Figure 4-1. There are two jumpers provided on J2. The

lower jumper configures Port1 and the upper configures Port2. Each

jumper can be placed in one of three positions, see Figure 4-1. The three

positions match cable impedance of 100, 120, and 150 ohms. If the

characteristics of the cable you are using are unknown check with the

cable manufacturer for the resistance setting. The manufacturer’s name

is usually printed on the cable cover.

Connector J5

Connector J5 is the impedance matching jumper for the 10Base2 (BNC)

connector labeled P1 on the ANCB board. The connector is a 2-position

(4-pin) connector. Pin 1 is denoted by a dog-ear that is silk-screened in a

rectangle near J5. The pins are numbered 1 to 4 in the clockwise

direction.

End point devices should be terminated with a 50-ohm resistor.

Impedance termination for

Ethernet 10Base2:

Devices that are not on the end point require no termination resistors.

When the 10Base2 connector is not in use (i.e. no cable connected) the

connector should be terminated with a 25-ohm resistor to prevent

spurious errors from being generated on the 10BaseT connector. This is

necessary since both the 10Base2 and 10BaseT connectors are

connected to the same Ethernet Hub chip on the ANCB board.

2000592-001 Troubleshooting • 47

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Siemens ADVANCE NETWORK COMMUNICATIONS BOARD/DATANET 20005 User Manual Page 57