Visible at a distance: The Kvaser U100’s smart LEDs

22/04/2021 by Akshay Joshi

Interface LEDs can be difficult to see at a distance. Kvaser’s engineering team sought to resolve this issue with two high-visibility LED bars on the Kvaser U100 that can be seen from several metres away.

One bar shows ‘transmit’, Tx, the other ‘receive’, Rx. Different colours and blink patterns show different information. For example, a steady green light (for power) shows that the device is working correctly.

The size of the LED bar indicates bus load. If only half the LED is illuminated in yellow (for traffic), the interface is handling 50% bus load.

Red signals errors and overruns, so the engineer knows immediately when something is wrong and in which traffic direction. White light signals an alert and blue is for system configuration and of course if there’s no light, the power supply should be checked.

See below for a detailed breakdown of what the Kvaser U100 LEDs mean.

UNDERSTANDING THE KVASER U100 LEDs

Definitions of LED states and colors

The Kvaser U100 has one Tx LED Bar and one Rx LED Bar. Each LED Bar has a status area, the Tx LED Bar has a status area towards the USB end of the bar, and the Rx LED bar has a status area towards the CAN end of the bar. This is shown in Figure 1.

Figure 1: The Tx and Rx LED bars on the Kvaser U100 includes status areas.

The Tx LED bar lit area grows from the USB end of the LED bar towards the CAN end of the bar as CAN Tx traffic is increased. Likewise, the Rx LED bar lit area grows from the CAN end of the LED bar towards the USB end of the bar as the message rate of the received traffic is increased, see Figure 2 below.

In this example the unit is transmitting data, which shows a yellow Tx status area. No CAN traffic is received and as such the Rx status area is green.

Figure 2: The Tx LED bar lights up from the USB side to the CAN side of the unit,while the Rx LED bar lights up from the CAN side to the USB side of the unit.

The total size of the LED bars are indicating the current bus load, e.g. Figure 2 shows only receiving CAN messages at 50% bus load.

Figure 3 shows two different bus load conditions. The image on the left shows the unit transmitting and receiving data corresponding to 50% bus load in each direction for a total of 100% bus load. The image on the right shows the unit transmitting data corresponding to 100% bus load. Both images indicate a bus load of 100%.

Figure 3: The total size of the LED Bars is proportional to the bus load. Both images indicate a bus load of 100%.

Definitions of Information Types and States

A Kvaser U100 device has two traffic LED bars where part of each LED bar is also used as a status area. Different colors are used for different types of information and different blink patterns define the current state see table 1 and table 2

Table 1: Different types of information.

Table 2: Definitions of the indicator states.

Interface mode

The device is in interface mode when connected to the PC via USB. If the status area is presenting a steady green light, the device is in interface mode and is working correctly.

When connected to the computer for the first time, the status area will Fast Blink with blue light until the Kvaser Driver is installed and the device has automatically received a USB configuration.

Table 3 summarizes the information shown in interface mode.

Table 3: LED inidications in interface mode.