ARC Network Design¶
An ARC’s current requirements vary depending on the voltage supplied to it. For example, an ARC-2e with a 15 VDC supply uses approximately 115 mA, while with 8 VDC it uses approximately 230 mA. As the voltage varies from 15 VDC to 8 VDC, the current requirement increases accordingly.Note: The voltage range for all ARCs is 8 to 30 VDC. Symetrix units' ARC ports provide 24 VDC.
The following table provides at-a-glance cable length limitations based on DC power (the table is not relevant if only RS-485 is distributed) and assumes 24 gauge CAT5/6 cabling. The lengths for multiple ARCs on a single chain assume equal distance for each cable segment between ARCs. This table is intended for quick reference only. For more detailed configuration scenarios, Symetrix has made available a Microsoft Excel spreadsheet to help system designers determine power requirements based upon cable length, number of ARCs, and the power supply to be used. This spreadsheet can be downloaded from the Symetrix Technical Support pages here.
| ** ** | CABLE SEGMENT LENGTH LIMITATIONS FOR ARC POWER OVER CAT5 CABLE | |||
| ARC TYPE | ||||
| Number of ARC’s on chain | ARC-3 | ARC-2e | ARC-K1e | ARC-SW4e |
| 1 | 3000’ | 3000’ | 3250’ | 3250’ |
| 2 | 1100’ | 1200’ | 3000’ | 3000’ |
| 3 | 550’ | 700’ | 1250’ | 1250’ |
| 4 | 200’ | 250’ | 400’ | 400’ |
*Note- These numbers are based on ARCs attached to an Edge, Radius, or other device supplying 24V and at least 500 mA.
If power is not distributed over CAT5/6, each RS-485 chain is limited to 1000 feet / 304 m in a star network configuration and 4000 feet / 1219 m in a daisy-chain network configuration. Longer distances may be possible using third party RS-485 extender products.
The total number of ARCs that can be daisy chained and fed power from an ARC port may be limited depending on ARC type and cable distances. An ARC-PSe Rack Mount Power Supply may be used to accommodate a larger number of ARC Wall Panels.
WARNING: When designing an ARC network, one must be careful not to double power any ARCs. If all pins on the CAT5/6 connections are used, power can travel over the CAT5/6 cable and reach any ARC on that particular chain. Power over CAT5/6 could potentially come from the ARC that is powered locally (via a custom wired cable using the pinout above) and then daisy-chained via CAT5/6 to other ARCs, or from a powered ARC port on a Symetrix unit or ARC-PSe (preferred). In general, we recommend only supplying power from the start of a chain (a Symetrix unit or an ARC-PSe).