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Anleitung Zusammenfassung
The male end of the BNC tee connector is used to connect directly to the host or to the transceiver. The female ends of the tee connector must be connected to another part of the segment or to a terminator. Page 2-1 INSTALLATION Since the ports on the module are internally terminated, the end of the segment that will be connected to the module will not be a tee connector or terminator. 2.2.2 Thin-net Segments (THN-MIM7593 only) The following network design guideline must be followed when connecting 75 or 93 ohm coaxial cable segments to the THN-MIM7593. If not, unsatisfactory network performance may result. • The length of the 75 or 93 ohm coaxial cable segment is dependent on signal loss from one end of the cable segment to the other. Signal loss must not exceed 4 db when measured with a 5 MHz sine wave or 6.5 db when measured with a 10 MHz sine wave. • A 75 or 93 ohm coaxial cable segment will only support point to point communication, from one Ethernet device to the THN-MIM7593. No other Ethernet devices are allowed on the segment. • The far end of the 75 or 93 ohm coaxial cable segment must be terminated with a 50 ohm terminator. This will ensure that the Ethernet device on the segment will receive the proper collision detection signal in the event of a collision. • The Ethernet device should be connected as close as possible to the terminator on the far end of the 75 or 93 ohm coaxial cable segment. This will ensure that impedance mismatches due to reflection can be predicted. • The BNC ports of the THN-MIM7593 are connected to earth ground. This eliminates the need for grounding the segment connected to the module. • Impedance mismatches may occur, resulting in signal degradation, due to the 75 or 93 ohm coaxial cable segment being connected to a 50 ohm terminator. This may result in: a. Increased jitter on the segment, ranging from +/-3 to +/-6 ns, depending on the mismatch b. Under certain conditions false collisions may be created. Page 2-2 INSTALLATION • The THN-MIM7593 does not report false collisions to the IRM. However, if a non-Cabletron Systems Ethernet device is connected to the segment, it is possible for false collisions to be generated. Non-Cabletron System devices should be thoroughly tested before using them with the THN-MIM7593. 2.2.3 Thick-net Segments • 50 ohm Ethernet type coaxial cable must be used when making up thick-net cable segments. • Each thick-net cable segment connected to a THN-MIM module must be no longer than 500 meters (1640 feet) in length. When making up networks requiring shorter cable runs, Ethernet standard length 23.4, 70.2, and 117 meter cable sections should be used. These cable sections may be connected together by a barrel connector to form a cable segment. Use of non-standard cable lengths may result in impedance mismatches causing reflections to occur. These reflections may cause data errors. • A 50 ohm terminator must be connected to the far end of the thick segment. • A BNC to N-Series adaptor must be connected to the applicable BNC port to attach the thick-net segment to the module. • A maximum of 100 transceivers may be attached to a thick-net cable segment, and these transceivers must be at least 2.5 meters apart throughout the length of the cable. Transceivers should be placed on the black bands that run along the cable that are marked at 2.5 meter intervals. • For safety, only one end of a thick-net segment should be connected to earth ground. Connection to earth ground at more than one point on the segment may allow for the occurrence of dangerous ground currents. The BNC ports of the THN-MIM are connected to earth ground. This eliminates the need for grounding a thick-net segment connected to the module. Page 2-3 INSTALLATION 2.3 INSTALLATION Install the THN-MIM into the MMAC as follows: CAUTION: Observe all electrostatic precautions when handling the THN-MIM. Static discharges will damage the module. 1. Remove the unit from the shipping box. 2. Slide the two foam end caps off the unit. 3. Remove the unit from the protective plastic bag and set the THN-MIM in a static free area. Save the shipping box and materials in case the module has to be reshipped. 4. Slide the module into the MMAC card cage. 5. Secure the module to the MMAC by turning the knurled knobs. CAUTION: Be sure the THN-MIM is firmly attached to the MMAC by turning the knurled knobs. Failure to do so may result in improper operation. Install the thick or thin-net cable segment(s) to the BNC ports(s) on the module. If a thick-net cable segment is attached to a port on the module, a BNC to N-Series adaptor must be attached to the port. The THN-MIM is now ready for operation. It is recommended that the segments be tested prior to transmitting data. Refer to Section 3.2 - INSTALLATION CHECKOUT. Page 2-4 TESTING AND LANVIEW CHAPTER 3 TESTING AND LANVIEW 3.1 INTRODUCTION This section lists procedures to ensure that the segments connected to the Cabletron Systems THN-MIM are operating proper...