Honeywell W7750A specifications Lay Out Communications and Power Wiring, Lonworks Bus Layout

EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER

Each LONWORKS Bus segment is set up with two unused nodes to allow for a CARE/E-Vision operator terminal to be connected to the LONWORKS Bus. Multiple CARE/E-Vision

terminals can be connected to the LONWORKS Bus at the same time. Table 7 summarizes the LONWORKS Bus segment configuration rules.

Table 7. LONWORKS® Bus Configuration Rules And Device Node Numbers.

One LONWORKS Bus Segment Example	Maximum Number of Nodes Equals 62
One Q7750A Excel 10 Zone Manager	1 node
Port for operator terminal access (CARE/E-Vision)	1 node
Maximum number of Excel 10s	60 nodes
Total	62 nodes
Two LONWORKS Bus Segments Example	Maximum Number of Nodes Equals 125
One Q7750A Excel 10 Zone Manager	1 node
One Q7751A,B Router	2 nodes (1 in each Bus Segment)
Ports for operator terminal access (two CARE/E-Vision	2 nodes (1 in each Bus Segment)
terminals)
Maximum number of Excel 10s in segment number one	60 nodes
Maximum number of Excel 10s in segment number two	60 nodes
Total	125 nodes

Refer to the LONWORKS Bus Wiring Guidelines form, 74-2865 for complete description of network topology rules and the maximum wire length limitations. If longer runs are required, a Q7740A 2-Way or Q7740B 4-Way Repeater can be added to extend the length of the LONWORKS Bus. A Q7751A,B Router can be added to partition the system into two segments and effectively double the length of the LONWORKS Bus. Only one router is allowed with each Excel 10 Zone Manager, and each network segment can have a maximum of one repeater.

In addition, all LONWORKS Bus segments require the installation of a 209541B Termination Module for a singly terminated LONWORKS Bus or two 209541B Termination Modules for a doubly terminated LONWORKS Bus. For more details on LONWORKS Bus termination, refer to the LONWORKS Bus Wiring Guidelines form, 74-2865, or see Application Step 3. Lay Out Communications and Power Wiring, and the LONWORKS Bus Termination Module subsection in Application Step 4.

Step 3. Lay Out Communications and Power Wiring

LONWORKS® Bus Layout

The communications bus, LONWORKS Bus, is a 78-kilobits per second (kbps) serial link that uses transformer isolation and differential Manchester encoding. Approved cable types for LONWORKS Bus communications wiring is Level IV 22 AWG (0.34 mm2) plenum or non-plenum rated unshielded, twisted

pair, solid conductor wire. For nonplenum areas, use Level IV 22 AWG (0.325 mm2), such as U.S. part AK3781 (one pair) or U.S. part AK3782 (two pair). In plenum areas, use plenum- rated Level IV, 22 AWG (0.325 mm2) such as U.S. part AK3791 (one pair) or U.S. part AK3792 (two pair). See Tables 9 and 11 for part numbers. Contact Echelon Corp. Technical Support for the recommended vendors of Echelon approved cables. The FTT communications bus, LONWORKS Bus, supports a polarity insensitive, free topology wiring scheme that supports T-tap, star, loop, and mixed bus wiring.

LONWORKS Bus networks can be configured in a variety of ways, so refer to the LONWORKS Bus Wiring Guidelines form, 74-2865 for complete description of network topology rules and Table 7. Fig. 19 and 20 depict two typical LONWORKS Bus network topologies; One has only one doubly terminated LONWORKS Bus segment that has 60 nodes or less, and one showing two singly terminated LONWORKS Bus segments that has 120 nodes or less (60 MAX per each segment). The bus configuration is set up using the Network Manager tool from within CARE (see the CARE Excel 10 Zone Manager User’s Guide, form 74-1392).

NOTE: For wiring details see the LONWORKS Bus Termination Module subsection in Step 4. For wall module wiring, U.S. part AK3782 (non-plenum) or U.S. part AK3792 (plenum) can be used. For a LONWORKS Bus that is a doubly terminated daisy- chain, these cables contain two twisted pairs (one for the run down to the wall module, and one for the run back up to the controller) for ease of installation.

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