Troubleshooting Center

General Information

Calculate expected “At Rest” current draw on each wire path and each LDI or SDI interface.

• FD-101 = 0.5 mA
• FD-102 = 0.5 mA
• FD-202 = 1.0 mA
• FD-401 = 1.0 mA
• FD-601 = 1.0 mA

Prior to troubleshooting when using a clamp meter, make sure you know the static current draw of the wire path or sections of wire path you will be troubleshooting.

(1) To calculate the static current draw at an individual wire path section, add the number of decoders that are downstream from the test point, and multiply it by the current draw of each decoder to determine the total calculated current draw of the wire section after the test point.

(2) To calculate the static current draw of an entire wire path, add the number of decoders on the entire wire path, and multiply it by the current draw of each decoder to determine the total calculated current draw of the wire path.

(3) To calculate the static current draw of an entire interface, add up all calculated wire path current draws that are connected to the interface.

Note: If the wire path has been looped, you must break the loop in order to properly troubleshoot current draw using a clamp meter.

Example

BLUE WIRE

• 100 FD-101 x 0.5 mA = 50 mA
• 25 FD-202 x 1.0 mA = 25 mA
• 10 FD-401 and FD-601 = 10 mA
• Total Blue Wire current = 85 mA

RED WIRE

• 80 FD-102 x 0.5 mA = 40 mA
• 20 FD-202 x 1.0 mA = 20 mA
• 15 FD-401 and FD-601 = 15 mA
• Total Red Wire current = 75 mA

Total Current for LDI or SDI = 85 + 75 = 160 mA