CM44P datasheet(13/60 Pages) EH

13 / 60 page

Liquiline CM44P

Endress+Hauser

Heartbeat and NAMUR category

The Heartbeat status indicates the sensor or device condition while the NAMUR categories (F, C, M,

S) assess the reliability of the measured value. The two conditions can correlate but do not have to.

• Example 1

• The number of remaining cleaning cycles for the sensor reaches 20% of the defined maximum

number. The Heartbeat symbol changes from

to . The measured value is still reliable so the

NAMUR status signal does not change.

• If the maximum number of cleaning cycles is exceeded, the Heartbeat symbol changes from

to . While the measured value can still be reliable, the NAMUR status signal changes to M

(maintenance required).

• Example 2

The sensor breaks. The Heartbeat status changes immediately from

and the NAMUR

status signal also changes immediately to F (failure).

Heartbeat Monitoring

Sensor data from Memosens sensors are transmitted via the EtherNet/IP, PROFINET, PROFIBUS DP,

HART, Modbus RTU and Modbus TCP fieldbus protocols. These data can be used for predictive

maintenance, for instance.

Examples include:

• Total hours of operation

• Hours of operation with very high or very low measured values

• Hours of operation at high temperatures

• Number of steam sterilizations

• Sensor identification

• Calibration information

For detailed information on "Ethernet/IP communication", see the product pages on the Internet

(→ SD01293C).

For detailed information on "Modbus communication", see the product pages on the Internet (→

SD01189C).

For detailed information on "PROFINET communication", see the product pages on the internet

(→ SD02490C).

For detailed information on "PROFIBUS communication", see the product pages on the Internet

(→ SD01188C).

More detailed information on HART communication is provided on the product pages on the

Internet (→ SD01187C).

Heartbeat Verification

Heartbeat Verification makes it possible to verify the correct operation of the measuring device

without interrupting the process. This verification can be documented anytime.

Sensor Check System (SCS)

The Sensor Check System (SCS) monitors the high impedance of the pH glass. An alarm is issued if a

minimum impedance value is undershot or a maximum impedance is exceeded.

• Glass breakage is the main reason for a drop in high impedance values

• The reasons for increasing impedance values include:

• Dry sensor

• Worn pH glass membrane

Process Check System (PCS)

The process check system (PCS) checks the measuring signal for stagnation. An alarm is triggered if

the measuring signal does not change over a specific period (several measured values).

The main causes of stagnating measured values are:

• Contaminated sensor, or sensor outside of medium

• Sensor defective

• Process error (e.g. through control system)

Self-monitoring functions

Current inputs are deactivated in the event of overcurrent and reactivated once the overcurrent

stops. Board voltages are monitored and the board temperature is also measured.

CM44P Datasheet(PDF) 13 Page - Endress+Hauser Group Services AG

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