X20 system modules • Analog input modules • X20AI2438
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X20 system User's Manual 3.10
4.3.7.9.5 General information
The X20AI2438 module has two independent electrically isolated channels with integrated HART modems. Both
channels can be used to read in an analog signal and handle HART communication. Two registers need to be
configured for one analog signal. The two channels operate independently, so two registers must be configured
per channel to be used.
The current input signals (0 to 25 mA) can be displayed in various formats and used as conventional analog inputs.
The integrated HART modems retrieve digital information from the memory on the HART slave using the same
physical lines that modulate the HART signals.
When using the 0 to 25 mA current input variant, the module is conceived as a HART master for 2 channels (loops),
with FSK modulation of the HART protocol and sensor supply for max. 4 slaves per channel.
Each channel can use one of the following connection variants:
•
Connection of one HART node (point-to-point) with evaluation of the analog signal and output of 4 HART
process variables OR
•
Connection of up to 15 HART nodes in multidrop mode with output of the primary HART variable from
activated nodes
Specific features:
•
Electrical isolation by channel
•
Up to 4 or 15 HART input variables per channel
•
Configurable sampling rate (input filter) to transfer HART and analog signal without interference (default:
50 Hz or 20 ms)
•
Internal supply with short circuit protection <30 mA per channel
•
Selective line monitoring can be enabled for: open line (<2 mA), underflow (<3.6 mA) or overflow (>21 mA)
of a configurable threshold
•
Selectable error strategy (static replacement value or retention of the last permitted value)
•
Cyclic "HART status" polling (HART command 0), the status information received is made available for
channel diagnostics
•
Compatible with an additional secondary master in the HART network (module acts as the primary master)
•
"HART communication error bit" (shows loss of HART connection if a connection had already been estab-
lished successfully)
•
Optional: Burst mode for one node per channel
•
Optional: Cyclic polling of "HART variables" (HART command 3 or 9)
•
Optional: Sensor supply for max. 4 nodes per channel in the multidrop variant
•
Optional: FlatStream functionality (module acts as bridge for HART packets)
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