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George’s CBAS Tips, April 2020


What do the lights on the LX controller mean?

Most Computrols hardware products include various LEDs – these lights can be very helpful in providing visual feedback of various controller conditions and the status of communication channels.

The LX controller features several differences and improvements over the X-line with regards to LED indicator light functions.

LX Control board 1

Controller Startup

When the LX  is first turned on the Power led will illuminate solid green, the Host-RX and Sec-RX lights will illuminate solid red and the Run light will blink red during the initial startup process. 

Once the controller is running, the Run light will blink steady green if the controller contains a database. If there is no database present in the controller the Run led will alternate between a double and single blinking green pattern.

The Run light will stay a steady red while a database is in the process of downloading to the controller and will blink 3 times once the database has completed the download process.

Network Lights – IP

The RJ45 connector on the LX controller now has Link and Activity lights built into the connector itself, viewable from the top of the controller. The Link light is on the left side of the connector and will illuminate solid yellow when the controller is connected to any type of network equipment. The Activity light is on the right side of the connector and will flash intermittently whenever network traffic is observed.

Network Lights – RS485

Host and Sec refer to the Host and Secondary channels.

HL will blink green when a High-Level message or token is sent out on the RS485 channel. A High-Level message is a command from the CBAS software.

TX will blink green when the LX transmits a packet to a controller on the RS485 channel.

RX will blink red when the LX receives a packet from a controller on the RS485 channel.

Troubleshooting RS485

The TX and RX lights are a valuable troubleshooting tool and should always be consulted first when a 485 channel will not work. If your controller is transmitting (TX light blinking), then the LX is trying to communicate with other controllers on the channel. The TX light will not blink if there is no channel downloaded to the controller, no controller programmed on the channel or if the channel is not properly licensed.

If the RX light is not blinking, this is usually an indication that the LX controller is not receiving communications on the RS485 channel. Possible causes could be a wiring issue or misconfiguration of the other controllers on the channel. If the other network devices have RX and TX lights on it, you should be seeing their RX lights blink when the LX transmits and vice-versa.For more information on the LX line of controllers, contact for a copy of the LX Manual PDF or download it from our documentation page.

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