Section 12 – Power Requirements12-9A Sensor Load for a SIM or PID Gateway that Includes Horn/StrobesTo determine the maximum length of the trunk cable for a sensor load that includes horn/strobes,perform the following steps:Step Action1 Make sure that gateway will have at least 9.7 volts from the RS-485 bus.2 Get the gateway trunk load in mA from Table 1 for a PID gateway, or Table 2 for a SIMgateway.3 Locate this value of current on the vertical axis of the curves shown in Figure 12-5.4 Using a straight edge, project across to the right until you meet the curve that representsthe voltage being applied to the gateway. Use the value of voltage obtained from the loaddiagram.5 Using the straight edge again, project a line straight downward to the horizontal axis.The length that is indicated is the maximum length that can be used for the trunk cablefor either a PID gateway or a SIM gateway.6 Repeat the steps for each gateway.10.2V10.1V10.0V9.9V9.8V9.7V010020030040050060070080090010000 100 200 300 400 500 600 700Maximum Length of Gateway Trunk (feet)Horn/Strobe Load (ma)Figure 12-5: Determining the Maximum Length of Quad Trunk for SIM/PID Gateway withHorn/StrobesDetermining the Control Unit Power Supply LoadUse the tables below to calculate the total current for the RS-485 Bus #1, RS-485 Bus #2, Aux Relay(terminal 10 when wet), Bell 1, and Bell 2 outputs. In each worksheet, multiply each device's standbyand/or alarm current by the number of units used.
