EXCEL 10 W7761A INPUT/OUTPUT DEVICE
It is important to understand these interrelationships early in the job engineering process to ensure implementing when configuring the controllers. (See Application Step 6. Configure Devices, for information on the various Excel 10 parameters and on Excel 10 point mapping.)
Step 2. Determine Other Bus Devices Required
A maximum of 62 nodes can communicate on a single E-Bus segment. Each W7761A (RIO), W7750 (CVAHU), W7751 (VAV) Controller or T7780 Wall Module constitutes one node. If more nodes are required, a Q7751A Router is necessary. Using a router allows up to 125 nodes, divided between two E-Bus segments. The router accounts for two of these nodes (one node on each side of the router); a Q7750A Excel 10 Zone Manager takes one node and two nodes are available for operator terminal nodes, leaving 120 nodes available for Excel 10 Controllers and T7780 Wall Modules. All 120 controllers and T7780 Wall Modules are able to talk to each other through the router. A Q7750A Excel 10 Zone Manager is required to connect the E-Bus to the standard EXCEL 5000® System C-Bus. Each Excel 10 Zone Manager can support no more than 120 Excel 10 Controllers and T7780 Wall Modules. This limit is set in the Excel 10 Zone Manager database as an absolute maximum.
Each E-Bus segment is set up with two unused nodes to allow for a CARE/E-Vision or Hand Held Tool (HHT) to be connected to the E-Bus. Multiple CARE/E-Vision or HHT terminals can be connected to the bus at the same time. Table 4 summarizes the E-Bus segment configuration rules.
Table 4 . E-Bus Configuration Rules And Device Node Numbers.
One E-Bus Segment Example | Maximum Number of Nodes Equals 62 |
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One Q7750A Excel 10 Zone Manager | 1 node |
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Port for operator terminal access (CARE/E-Vision or HHT) | 1 node |
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Maximum number of Excel 10s and T7780s | 60 nodes (Only T7780 Wall Modules are E-Bus nodes) |
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Total | 62 nodes |
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Two E-Bus Segments Example | Maximum Number of Nodes Equals 125 |
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One Q7750A Excel 10 Zone Manager | 1 node |
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One Q7751A Router | 2 nodes (1 in each Bus Segment) |
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Ports for operator terminal access (two CARE/E-Vision or HHT | 2 nodes (1 in each Bus Segment) |
terminals) | |
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Maximum number of Excel 10s and T7780s in segment number | 60 nodes (Only T7780 Wall Modules are E-Bus nodes) |
one | |
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Maximum number of Excel 10s and T7780s in segment number | 60 nodes (Only T7780 Wall Modules are E-Bus nodes) |
two | |
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Total | 125 nodes |
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Refer to the E-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 E-Bus. A Q7751A Router can be added to partition the system into two segments and effectively double the length of the E-Bus. Only one router is allowed with each Excel 10 Zone Manager and each network segment can have a maximum of 1 repeater. In addition, all E-Bus segments require the installation of a Bus Termination Module for a singly terminated E-Bus or two Bus Termination Modules for a doubly terminated E-Bus. For more details on E-Bus termination, refer to the E-Bus Wiring Guidelines form, 74-2865, or see Application Step 3. Lay Out Communications and Power Wiring, and the E-Bus Termination Module subsection in Application Step 4.
Step 3. Lay Out Communications and Power Wiring
E-Bus Layout
The communications bus, E-Bus, is a 78-kilobit serial link that uses transformer isolation and differential Manchester encoding. Approved cable types for E-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 (0.34 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 (0.34 mm2) such as U.S. part AK3791 (one pair) or U.S. part AK3792 (two pair). See Tables 9 and 10 for part numbers. Contact Echelon® Corp. Technical Support for the recommended vendors of Echelon® approved cables. The FTT communications bus, E-Bus, supports a polarity insensitive, free topology wiring scheme that supports star, loop, and/or bus wiring.
E-Bus networks can be configured in a variety of ways, so refer to the E-Bus Wiring Guidelines form, 74-2865 for a complete description of network topology rules and Table 4. Fig. 9 and 10 depict two typical E-Bus network topologies; one as a singly terminated bus segment that has 60 nodes or less, and one showing a doubly terminated segment. The bus configuration is set up using the Network Manager tool from within CARE (see the CARE User’s Manual form, 74-5587 or Excel E-Vision User’s Guide form, 74-2588).
