Distech Controls ECLYPSE APEX, Руководство пользователя

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129 ECLYPSE APEX
About Tuning the Max Master Parameter
To prevent the passing of the token to unused MAC Addresses situated after the final Master device,
the Max Master parameter must be set. By default, the Max Master for an ECY Series Controller or a
Supervisor is set to 127 which allows for the theoretical maximum of 127 devices besides the Data
Bus Master to be connected to the data bus.
In practice, the actual number of devices connected to a data bus is far less, resulting in a gap be-
tween the highest MAC Address of any device connected to the data bus and the value set for Max
Master. This gap unnecessarily slows-down the data bus with Poll for Master requests.
When commissioning a BACnet MS/TP Data Bus, it is useful to start with the Max Master set to 127 so
as to be able to discover all devices connected to the data bus. Then, once all devices have been dis-
covered and the MAC Addressing is finalized by eliminating any gaps in the address range, set the
Max Master (maximum MAC Address) in the ECY Series Controller and in the Supervisor to the high-
est Master device’s MAC Address number to optimize the efficiency of the data bus.
Setting the Max Master and Max Info Frames
The Max Master and Max Info Frames are parameters used to optimize a BACnet MS/TP Data Bus.
This is set in the ECY Series Controller and separately with the Supervisor for each connected BAC-
net MS/TP device.
For the ECY Series Controller, set the Max Info Frames to 20 in the screen shown in BACnet Settings
of the
Network MS/TP Ports as this is a device that will make more requests for service from other de-
vices on the network. In general, according to the way a device is programmed, the Max Info Frames
may have to be set to a higher value than for other devices. For example, when Roof Top Unit Con-
trollers are used with VAV controllers that use
gfx Applications code, they should also have their Max
Info Frames set to a higher value such as 5, as Roof Top Unit Controllers will poll many VAV con-
trollers for information.
To set the Max Master and Max Info Frames for BACnet MS/TP devices (for example, an ECB series
controller), use a Supervisor to do so. See the Network User Guide for more information.
Default Device Instance Number Numbering System for Distech
Controls’ Controllers
By default, controllers from Distech Controls automatically self-assign a Device Instance number gen-
erated from the unique MAC Address assigned to the controller during installation. The Device In-
stance number is calculated as follows:
Device Instance number = 364 X 1000 + MAC Address
Where 364 is Distech Controls unique BACnet Manufacturer ID.
This Numbering system is sufficient for a BACnet network that has only one ECY Series Controller.
For larger BACnet networks that have more than one controller (to form a BACnet intranetwork), set
the MAC Addresses, Device Instance Numbers and Network Numbers according to the numbering
scheme below.
Adopting a Numbering System for MAC Addresses, Device Instance
Numbers, and Network Numbers
Good network planning requires a well-thought-out numbering scheme for device MAC Addresses,
Device Instance Numbers (DI), and Network Numbers. We recommend the following scheme, as it
reuses the MAC Address and Network Number in the Device Instance number to make it easier for a
network administrator to know where a device is located in the network. This is shown below.
BACnet MS/TP Communication Data Bus Fundamentals