PTI Security Systems specifications for Digitech RS-485 systems

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The RS-485 network is used by the Syscon to communicate with the various access control devices at the site. An example of such a network is shown below. The blue line is the RS485A type of communications used for electronic devices. Generally, limited to four thousand total feet of wire length. Used for connecting the Falcon XT to AI Devices. data wire.

RS485 Network Example 1.png
  1. Connection is made using an 18 Gauge 2 or 4 conductor cable[1], that has a foil shield and a bare drain wire. Do not substitute any other wire type.
  2. The RS-485 network will be a continuous circuit, with no branches[2]
    1. Four conductor cable is only used when it is necessary to "loop back" the RS485 network to avoid having extra branches.
    2. Because it's wire is typically very short (<20 feet) the RS-485 cable to the DigiGraphics does not count as a "branch".
      1. Each end of the circuit will be terminated with the appropriate jumper or switch setting (depending on what type of device is at the end).
      2. The specified cable is used for connecting the devices, and that the shield wire is connected at both ends to connector P2. At the Syscon end the shield wire is connected to a valid earth ground. Do not connect the shield wire to earth ground at any location other than the Syscon.
      3. maximum total cable distance of the RS-485 network is 4000 feet.

      Notes

      1. Four conductor cable is only used when it is necessary to "loop back" the RS485 network to avoid having extra branches.
      2. Because it's wire is typically very short (<20 feet) the RS-485 cable to the DigiGraphics does not count as a "branch".
        1. Each end of the circuit will be terminated with the appropriate jumper or switch setting (depending on what type of device is at the end).
        2. The specified cable is used for connecting the devices, and that the shield wire is connected at both ends to connector P2. At the Syscon end the shield wire is connected to a valid earth ground. Do not connect the shield wire to earth ground at any location other than the Syscon.
        3. maximum total cable distance of the RS-485 network is 4000 feet.

        Notes

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