Interconnection

Communications

The SITRANS LC 500 is equipped with HART communication protocol so that settings and values can be obtained and altered locally or remotely.

Typical PLC configuration with HART

power supply1

R2= 250

SITRANS LC 500

PC/laptop with Simatic PDM or HART communicator3

Diagnostics

The internal diagnostic functions continuously monitor the operation of the transmitter. An error signal is generated if a failure or irregularity occurs.

The SITRANS LC 500 sends the signal current according to the NAMUR NE 43 recommendation. During normal operation the current remains within the range from 3.8 to 20.5 mA. If the process exceeds its normal limits but is not in a fault or failure situation, the signal current will be outside the measurement range (4 to 20 mA) but will be limited to either 3.8 or 20.5 mA.

If a fault or a failure is detected, the signal current is set to either 3.6 mA or 22 mA, depending on the settings you have chosen. (This feature may be disabled by the user.)

1.Depending on the system design, the power supply may be separate from the PLC, or it may be part of the PLC.

2.A 250 Ohm resistor is required only when the PLC is connected to a HART modem or a HART communicator.

3.The HART communicator and a PCL/laptop computer cannot both be connected to the 4-20 mA loop simultaneously.

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SITRANS LC 500 – INSTRUCTION MANUAL

7ML19985GE01

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Siemens LC 500, Sitrans instruction manual Communications, Diagnostics, Typical PLC configuration with Hart