Comm5 wiring
BMTX-SVN01C-EN 49
Repeater limitations
The repeater has several limitations:
• Only one repeater can be used on a link.
• The use of a repeater doubles the maximum allowable wire length.
For example, when a repeater is used with a daisy-chain configura-
tion, the total wire length can be 9,000 ft (2,800 m) (with half the wire
length on either side of the repeater).
• The repeater is limited to 60 devices on either side of the link. The
total number of devices that can be attached to a repeater is 120.
• The repeater requires a definite earth ground. The installer should be
aware of this before making any power connections.
Repeater connections
Follow these guidelines when using a repeater:
• Refer to Figure 22 on page 45 (Figure 23 on page 46 for Trane-
approved, purple-jacketed wire) for an example of using a repeater to
create an extended daisy-chain configuration.
• Read the installation document that comes with the repeater: Comm5
repeater installation, #3270 3285.
• For information about terminating daisy-chain configurations, see
“Resistance termination for Comm5 links” on page 48.
Fiber-optic wiring for Comm5 links
Fiber-optic cable is used for Comm5 applications involving long distances,
inter-building cabling, and areas with a potential for high electrical noise
because there is little degradation of optic signals. The integrity of an
optic signal is maintained in the presence of several sources of electrical
noise, including lightning, EMI/RFI, voltage conductors, and ground
loops.
Trane requires duplex, 62.5 μm core glass fiber-optic cable with ST con-
nectors, which comes in a variety of types for specific applications, such as
indoor, outdoor, burial, aerial, and duct. You can order fiber-optic cable,
fiber-optic modems, ST-type crimp connectors, epoxy connectors, and
other accessories from approved suppliers in the Trane Buying Group.
IMPORTANT
Trane recommends that only qualified and experienced fiber-optic tech-
nicians prepare the fiber-optic end connectors and cable run lengths.
Improper methods may result in faulty communication due to signal
degradation (decibel loss). The signal degradation must be less than
14 dB on each fiber.
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