National Instruments 777518-120 Temperature Input Module

The National Instruments 777518-120, often referred to as the FP-TC-120, is a compact fieldpoint system-specific 8-channel thermocouple input module. With the use of this module, standard thermocouple kinds, such as J, K, T, N, R, S, E, and B, can be used to monitor temperature directly. The 777518-120 provides a dependable and effective temperature monitoring system with features including HotPnP (plug-and-play) operation, simple configuration, self-diagnostics, and automatic scaling to engineering units.

Each of the eight differential input channels in the 777518-120 shares a common ground reference, which is isolated from other modules within the FieldPoint system. The input channels are furnished with pull-up resistors on the positive terminal (IN+) and bias resistors to the isolated ground reference on the negative terminal (IN-) in order to assist the detection of open thermocouples. In order to link each channel to the isolated ground reference, the module additionally has a COM terminal. To provide accurate temperature readings, the input signals are filtered before being sampled using a 16-bit delta-sigma analog-to-digital converter (ADC).

The 777518-120 is capable of detecting open thermocouples and, upon detection of one, will indicate the error with a red LED indicator for the impacted channel. In addition, the module has two green status LEDs that are labelled POWER and READY. The POWER LED illuminates when power is applied to the connected network module and the module is placed into a terminal base or backplane. The READY LED then illuminates, signaling that the network module is in regular functioning mode, once the network module detects the 777518-120 and transfers the initial configuration data.

Built to withstand harsh conditions, the 777518-120 offers cold-junction correction and integrated linearization for thermocouple types that it supports. There are four voltage ranges available: ±25 mV, ±50 mV, ±100 mV, and -20 to 80 mV. 250 Vrms isolation voltage rating, 2,300 Vrms transient overvoltage protection between the inter-module communication bus and the I/O channels, and filtering against 50 and 60 Hz noise are additional features. This module is perfect for dynamic industrial applications where precision and dependability are critical since it can work in a temperature range of -40 to 70 °C and provides hot plug-and-play capability.