Disconnection Detection Function; Sensor Connection - Honeywell TC4S User Manual

2. Specifications
2.3. Characteristics of thermocouple temperature sensor input module

Disconnection detection function

2MLF-TC4S module measures temperature by directly connecting thermocouple
temperature sensor and has the diagnosis function to detect and display any
disconnection of a sensor connected.
1. In case of a disconnection between the sensors used/compensating cable and
module, LED (ALM) flickers every second and generates an error code. In addition,
LED (ALM) indication flickers every second even though cold junction
compensating sensor installed on the module's terminal block is separated or
destructed, hindering normal connection.
2. Channel wise detection of disconnect is possible. However, it is available for only
the channel(s) designated for operation. LED (ALM) is commonly used for every
channel. It flickers in case even one channel is disconnected.
3. The module detects and displays disconnection and it means that the following
cabling path will have partially bad connection, which requires taking measures.

Sensor connection

A thermocouple sensor can either be directly connected to the terminal of the module or
by using a compensating cable (type of cable depends on sensor type.) For the further
information on connecting the sensor, contact sensor manufacturer.
30 Isolated Thermocouple Input Module TC4S User's Guide
Honeywell
R200
September 2010