Pin assignments

The pin assignments for the RS-422 connectors and SDI-12 sensors are provided below.

RS-422 pin assignments

Round Turck connectors are used for RS-422 serial output between the LI-8250 Multiplexer and chambers. The RS-422 pin assignments are as follows:

LI-8250 Multiplexer power and communication port

This connection allows the LI-8250 Multiplexer to provide power and communication to LI-COR long-term chambers and to communicate with custom chambers. The pin assignment shown in Table G‑1 represents the female end of the power and communication port on the multiplexer.

Table G‑1. Pin assignment for the power and communication ports on the multiplexer.
  Connector Pin # LI-8250 Signal Name
1 RS422_RX-
2 RS422_TX-
3 RS422_TX+
4 +24VDC
5 Ground
6 +24VDC
7 RS422_RX+
8 Ground

8200-104/C Long-Term Chamber power and communication port

A 15 m RS-422 to RS-422 cable (part number 392-18852) is used to connect the LI-8250 Multiplexer to the 8200-104 Opaque Long-Term Chamber and the 8200-104C Clear Long-Term Chamber. This cable is included in the optional cable assembly (part number 9982-056). The pin assignment shown in Table G‑2 represents the male end of the power and communication port on the chamber.

Table G‑2. Pin assignment for the power and communication port on LI-COR long-term chambers.
  Connector Pin # Chamber Signal Name Wire Color
1 RS422_TX- White/Blue
2 RS422_RX- White/Brown
3 RS422_RX+ Brown
4 +24VDC Orange
5 Ground White/Green
6 +24VDC White/Orange
7 RS422_TX+ Blue
8 Ground Green

Bulkhead flying lead for custom chambers

A bulkhead flying lead (part number 310-19090) is available to connect the LI-8250 Multiplexer or 8250-01 Extension Manifold to a custom chamber for communication. The pin assignment shown in Table G‑3 represents the male end of the bulkhead.

Table G‑3. Pin assignment for the bulkhead flying lead that connects to a custom chamber.
  Connector Pin # Chamber Signal Name Bulkhead Wire Color
1 RS422_TX- White
2 RS422_RX- Brown
3 RS422_RX+ Green
4 +24VDC Yellow
5 Ground Gray
6 +24VDC Pink
7 RS422_TX+ Blue
8 Ground Red

Sensor connector pin assignments

To connect your own SDI-12 sensor to a 8200-104/C Long-Term Chamber, LI-COR provides an optional 2 m sensor connector to cable with flying leads (part number 392-18518). The pin assignment shown in Table G‑4 represents the male end of the Turck connector.

Caution: Be certain when wiring an SDI-12 sensor not to connect, short, or allow water to make contact with the white or gray wires. If the white or gray wires are connected, shorted, or make contact with water, all sensor communications may be corrupted, including the light sensor and thermistor temperature measurements.

Table G‑4. Pin assignment for the sensor connector.
  Connector Pin # Function Wire Color
1 +12 VDC power Brown
2 Thermistor input White
3 SDI-12 data Blue
4 Ground Black
5 Light sensor input Gray