FIGURE 8-1. BrHalf (2-wire half bridge) measurement error as a function of cable length
The heat shrink label on the CS240 cable provides the cable resistance (ohms). When using the
2-wire configuration, subtract this cable resistance from the measured resistance value. The value
included on the label is calculated with the following equation:
Cable resistance = 0.0274 ohm/feet x cable length (in feet)
Additional settling time may be required for cable lengths longer than 91 m (300 ft), where
settling time is the delay before the measurement is made. The 60 and 50 Hz integration options
include a 3 ms settling time; longer settling times can be typed into the
Settling Time
parameter in the
BrHalf4W()
or
BrHalf()
instruction.
8.2.2 CS240DM long cable lengths
Digital data transfer eliminates offset errors due to cable lengths. However, digital
communications can break down when cables are too long, resulting in either no response from
the sensor or corrupted readings. Maximum cable lengths depend on the number of sensors
connected, the type of cable used, and the environment of the application. Follow these
guidelines when using long cables:
CS240 and CS240DM PT-1000 Class A, Back-of-Module Temperature Sensors
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