Connecting the power and data cable

This section describes how to power up the LI-550, connect data cables, configure it, and get data from it.

LI-550F power and data

The LI-550F features a four-wire cable for power and data. The cable can be attached to a data logger or USB adapter.

Power and data wire assignments

Four unterminated wires exit the base of the LI-550F. The wires are color coded to indicate the purpose of each.

Table 3‑1. Wire assignments for the LI-550F.
Color Description
Yellow Power in; +5 to 30 VDC
Green RS-232 RX+; serial data receive
Red RS-232 TX+; serial data transmit
Black Ground and serial data return

Early models of the TriSonica Mini may have different color wires or additional wires. Refer to instructions accompanying the specially configured sensor for more information.

Connecting the LI-550F to the USB interface adapter

Use a USB-C cable (not included) to connect the adapter to your computer.

Note: The USB adapter is for scientific research and development use only. Do not use the USB adapter in wet locations.

Open the USB adapter case and connect the wires from the LI-550F to the terminal block. Then connect the adapter to a computer using a USB cable.

Table 3‑2. LI-550F-to-USB adapter wire colors and assignments.
Color Description (LI-550F) USB adapter connection
Yellow Power in; +5 to 30 VDC 12 V power out
Green RS-232 RX+; serial data receive TX+; serial data transmit
Red RS-232 TX+; serial data transmit RX+; serial data receive
Black Ground and serial data return Ground; data and power

A video demonstrating this connection is available at licor.com/support/LI-550/videos.html.

Figure 3‑1. USB adapter with the top cover removed. Wire colors represent the LI-550F.

LI-550P power and data

The LI-550P features a 12-pin circular connector. When connected properly, the connector should provide good protection against water ingress. Additional protection can be provided by the mounting configuration.

Important: Do not twist the cable during installation or removal. Doing so will damage the connector pins. To remove the cable, grasp the collar and pull it away from the anemometer.

Pre-made cables with connectors may be purchased from LI-COR in 1.25 and 10 meter lengths. Customized cables and can be made with the custom cable kit. Because this detachable cord carries both data and power, replacement cords or user-built cords must comply with the wiring and insulation specifications set out in the EIA Standard appropriate for the selected communication protocol.

Power and data wire assignments

Figure 3‑2 shows the socket assignments for the connector on the LI-550P. The internal wire colors and descriptions are given in Table 3‑4.

Figure 3‑2. 12-socket connector and assignments on the LI-550P.

Caution: The Power In wire is the only one that can handle voltages exceeding five volts. Applying excess voltage to other wires can damage the LI-550. Such damage is not covered by the warranty.

Table 3‑3. LI-550P socket descriptions and cable wire colors.
Socket Color Description
1 Brown Power In: 5 to 32 VDC.
2 Red Ground connection. Only one GND connection is required for proper operation. Multiple GND connections are provided for convenience.
3 Orange Synchronizing trigger input. This input allows multiple instruments to synchronize sampling to a common signal.
4 Yellow Serial transmit data output in EIA232 mode and TX+ data output in EIA422 mode.
5 Green Serial transmit data output TX- in EIA422 mode. Not used in EIA232 mode.
6 Blue Serial receive data input in EIA232 mode and RX+ data output in EIA422 mode.
7 Violet Serial receive data input RX- in EIA422 mode. Not used in EIA232 mode.
8 Gray URX; 3.3V LVTTL UART serial data input.
9 White Ground connection.
10 Black 232; Force single ended serial mode. When connected to GND, the LI-550 will start in EIA232 or LVTTL-UART mode with the settings of 115200,8,N,1 regardless of the software settings of the instrument.
11 Light Green UTX; 3.3V LVTTL-UART serial data output.
12 Pink Ground connection.

Connecting the LI-550P to the USB interface adapter

Note: The USB adapter is for scientific research and development use only. Do not use the USB adapter in wet locations.

The single-terminated blunt-cut cable is to connect the LI-550P to the USB adapter. Separate the brown, blue, yellow, red, and black wires from the bundle and strip 3 mm of insulation from the ends of each wire. Open the adapter case and connect wires to the terminal block as shown in Figure 3‑3.

Figure 3‑3. Separate the wire leads from the cable and connect to the USB adapter.
Table 3‑4. LI-550P-to-USB adapter wire colors and assignments.
Color Description (LI-550P) USB adapter connection
Brown Power in; +5 to 30 VDC 12 V power out
Blue RS-232 TX+; serial data transmit RX+; serial data receive
Yellow RS-232 RX+; serial data receive TX+; serial data transmit
Red and Black Ground and serial return Ground; data and power

Note: The cable contains 12 wires to accommodate the multi-protocol capable LI-550P. Some wires are not used in this application.

A video demonstrating this connection is available at licor.com/support/LI-550/videos.html.