Siemens Treadmill LC 500 사용자 설명서

7ML19985GE01

SITRANS LC 500 – INSTRUCTION MANUAL 

Page 15

The SITRANS LC 500 has three fault signalling options: 

• via the loop-current 
• via HART 
• via the solid-state output or solid-state relay. 

When using the mA signal, the SITRANS LC 500 operates according to NAMUR standards

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for fault signalling. The fault/failure signal can be triggered by a failure in the measuring 
system, such as:

• a checksum error
• a loss of signal caused by a defect in the module 
• a short circuit in the sensor
• a process failure if the level exceeds the limit settings and if the unit is 

programmed to detect this

You can set the Upper and Lower Sensor Limits (menus 0B and 0C) outside the Upper and 
Lower Range Value settings. In this case, if the process value is outside its nominal range 
(the span between LRV and URV), but still not at a fault/failure level, the continuous mA 
output will saturate to 3.8 mA or 20.5 mA. If the process value is outside the Upper or 
Lower Sensor Limits, this will be registered as a fault/failure.

Depending on the setting chosen for 2-state Fault Signalling (menu 08), the signal will go to 
either 3.6 mA (F: Lo) or to 22 mA (F:Hi). If you do not use communications to receive status 
information, we recommend enabling analog fault signalling (menu 08), in order to be 
warned if a fault or failure occurs. (This feature is disabled by default.)

See page 75 for 

. Each HART message is accompanied 

by a response code. It is then up to the Host to decide what to do in the case of a fault 
situation. The Host may decide to issue Command 48, which returns more detailed 
information.

The solid-state switch can be wired up to an external relay, to provide a second level of 
protection. It can then be used to activate a failure alarm, or a level switch. (See page 93 
for details of an application using SITRANS LC 500 as a level indicator, with the two-state 
output connected to a relay that activates a pump.)

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 See 

 on page 107 for more details.