ELECTRICAL CONNECTIONS
4
31
H250 M40
www.krohne.com
03/2020 - 4000640706 - MA H250-M40 R06 en
Load for HART
®
communication
The maximum load resistance is calculated as follows:
R
L
= (U
ext.
- 14 V) / 22 mA
Configuration
The ESK4A can be configured via HART
®
communication. DD (Device Description) for AMS and
PDM as well as a DTM (Device Type Manager) for PACTware
TM
are available for the
configuration. They can be downloaded free of charge from the website of the manufacturer.
The current flow rate can be transmitted using the integrated HART
®
communication. A flow
counter can be configured. Two limit values can be monitored. The limit values are assigned
either to flow values or to the counter overflow.
Self monitoring - Diagnostics
During both start-up and operation, a wide variety of diagnostic functions are performed
cyclically in the ESK4A in order to guarantee function reliability. When an error is detected, a
failure signal (high) is activated (factory setting: current >21 mA, optional configuration as failure
signal (low): < 3.6 mA) via the analogue output.
The failure signal is not activated for information and warnings. In addition more detailed
information can be requested via HART
®
(CMD#48).
Diagnostic functions (Monitoring):
•
Plausibility of FRAM data
•
Plausibility of ROM data
•
Working range of internal reference voltages
•
Signal detection of the measuring range of the internal sensors
•
Temperature compensation of the internal sensors
•
Calibration based on the application
•
Plausibility of counting value
•
Plausibility of physical unit, system and selected unit
•
Application diagnostics blocked float, pulsating flow, magnetic field interference
For ESK4A (HART
®
7) the diagnosis is reported in compliance with NE 107.
INFORMATION!
For HART
®
communication a load of at least 250
Ω
is required.
DANGER!
Use a twisted two-core cable to prevent electrical interference from impeding the DC output
signal.
In some cases a shielded cable may be necessary, e.g if noise levels higher than the NE 21
specification are anticipated.