ABB ACH550-01 User Manual page 143

ACH550 User's Manual
The figure below shows the ACH550 fieldbus control.
Fieldbus
adapter
Standard serial
link RS485
When using serial communication, the ACH550 can either:
• receive all of its control information from the fieldbus, or
• be controlled from some combination of fieldbus control and
other available control locations, such as digital or analog
inputs, and the control panel (operator keypad).
Serial communications
Other
devices
Slot 2
Either a plug-in fieldbus adapter
X1:28...32 module or the standard serial RS485
interface can be used at a time.
Data flow
Control word
reference
Status word
Actual values
Parameter R/W requests/responses
Fieldbus controller
Process
I/O
(cyclic)
Service
messages
(Acyclic)
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