Disconnection Detecting Function; Figure 8 - 3-Wire Rtd - Honeywell 2MLF-RD4A User Manual

ATTENTION
Non-linear characteristics: The resistance-temperature characteristics for
RTD sensor are presented in the Appendix 1: Table (JIS C1604-1997). The
characteristics table displays the resistance value of the sensor with respect
to the temperature, namely, the change of the resistance value for 1°C
changes the temperature. When the temperature changes by 1°C, the
change in resistance is not in constant width but in different width per section.
Such characteristics are called non-linear characteristics.
When consigned, the module is adjusted to Offset/Gain of each channel with
standard resistant source. To maintain the accuracy of the module, this value
is disabled for user to change

Disconnection detecting function

1. This function is achieved by a module used with the RTD temperature sensor
directly connected to the extended lead wire. It detects and displays disconnection
of the sensor and the extended lead wire. If any disconnection occurs between the
sensor used and extended lead wire, LED (ALM) will blink in a cycle of 1s and
generate an error code.
2. Disconnection can be detected only for the active channel. The LED (ALM) used is
common for all the channels. It will blink if one or more channels are disconnected.
3. The temperature sensor of a 3-wire RTD is as shown below. (The appearance varies
with the application.)
*A Disconnection: It is a disconnection between terminal A and terminal
a)
board of the module in the sensor.
b) *B Disconnection: It is a disconnection between terminal B (two for 3-wire
sensor) and terminal board of the module in the sensor, or a disconnection of
both A and B terminals with the terminal board of the module in the sensor.
R200 Resistance Temperature Detector 2MLF-RD4A User's Guide
September 2010
2.3. RTD input module characteristics
Figure 8 – 3-Wire RTD
Honeywell
2. Specifications
29