ACH550-UH User’s Manual 1-205
Embedded fieldbus
N2 protocol technical data
Overview
The N2 Fieldbus connection to the ACH550 drives is based on an industry standard
RS-485 physical interface. The N2 Fieldbus protocol is a master-slave type, serial
communication protocol, used by the Johnson Controls Metasys® system. In the
Metasys architecture the N2 Fieldbus connects object interfaces and remote
controllers to Network Control Units (NCUs).
The N2 Fieldbus can also be used to connect ACH550 drives to the Metasys
Companion product line.
This section describes the use of the N2 Fieldbus with the ACH550 drives’
connection and does not describe the protocol in detail.
Supported features
In the N2 Fieldbus protocol the ACH550 drive appears as a “virtual object”.
A virtual object is made up of:
• Analog Inputs
• Binary Inputs
• Analog Outputs
• Binary Outputs
• Internal values for Floating point, Integer, and Byte values.
The ACH550 drive does not support N2 Fieldbus communication “internal values”.
All of the Analog and Binary I/O objects are listed below, starting with N2 analog
input objects below.
Analog Input – The analog input objects support the following features:
• Analog Input actual value in engineering units
• Low Alarm limit
• Low Warning limit
• High Warning limit
• High Alarm limit
• Differential value for the hysteresis of the Alarms and Warnings
ACH550
Analog Inputs
Binary Inputs
Internal values, Float, Integer, Byte
Analog Outputs
Binary Outputs
Virtual Object
Metasys
Note: Metasys inputs are drive outputs and
drive inputs are Metasys outputs
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