LED Lines




Green Ethernet status LED




Yellow Ethernet status LED


L3 (SG)


LED output 3, Green status LED


L4 (SR)


LED output 4, Red status LED

Line functions defined by the application firmware are shown in blue

The EM120 has four LED control lines. All lines have the same internal structure and the LEDs should be connected to these lines as shown on the schematic diagram below. Maximum load for each line is 10mA.

EM120_led control

EG and EY lines reflect the status of the Ethernet port. The EG LED is normally ON, and is temporarily turned off whenever the EM120 receives a network packet. The EY is normally OFF, and is temporarily turned on whenever a data collision is detected on the Ethernet.

SG and SR lines are under firmware control and display various status information depending on what firmware is running at the moment. Follow the links below to learn more about the behaviour of these LEDs under different conditions:

SR/SG behavior in the monitor firmware.
SR/SG behavior in the application firmware.