Locating the SP-C in the middle of the RS-485 daisy chain.

Locating the SP-C in the middle of the RS-485 daisy chain.


Hazard of Electric Shock: Remove all power from all devices before removing any covers or doors of the system. Disconnect power at the device and at the power source.

Electrostatic Discharge Required: Always discharge static electricity from your person by touching metal prior to handling any hardware. Failure to do so may result in damage to devices.

Potential for Data Loss: The steps detailed in the resolution of this article may result in a loss of critical data if not performed properly. Before beginning these steps, make sure all important data is backed up in the event of data loss. If you are unsure or unfamiliar with any complex steps detailed in this article, please contact Product Support for assistance.


Are there restrictions on the location of the SP-C on the RS-485 bus?

Product Line

Security Expert


  • Security Expert Controller (SP-C, SP-AC1, SP-ACX, SP-C-WEB)
  • Security Expert Expander Modules


  • The SP-C Installation Manual shows the SP-C as the first device in a standard network communication connection. 
  • Locating the Security Expert controller in the middle of the RS-485 bus will reduce the amount of cable required.


You can put the controller in any position on the RS-485 chain. Ensure you use the correct cable type, the overall length does not exceed 900 meters (3000 feet) and the two ends are correctly terminated with EOL resistors. Refer to the Encrypted Module Network section in the SP-C Installation Manual - System Controller for more details.

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