Issue
Guidance is required to correctly configure a two-wire LTS80 Lini-Temp temperature sensor when connected to a 7756 PCU. The configuration differs depending on whether the sensor is connected to the upper board or the lower board of the PCU.
Product Line
TAC INET
Environment
- LTS80 Lini-Temp temperature sensor
- 7756 PCU – upper board
- 7756 PCU – lower board
Cause
The LTS80 Lini-Temp sensor is compatible with the I/NET product line. The upper and lower boards of the 7756 PCU use different resolution values, which require different configuration parameters.
Resolution
Common requirements (both boards):
- Install a 10 kΩ resistor in slot “A”.
- Refer to TCON 127: 7756 PCU Installation Guide for detailed installation information.
Upper board configuration:
- Fahrenheit:
- m = 0.21978
- b = -459.6
- Centigrade:
- m = 0.1221
- b = -273.0
- Set J22 to 15 VDC.
Lower board configuration:
- Fahrenheit:
- M = 0.0274669
- B = -459.8
The upper and lower boards use different resolution values. Configuration parameters must match the board in use and must not be interchanged.
