Appendix D: Johnson N2 Protocol Implementation Conformance Statement
RTU Open v5
CARRIER CORPORATION ©2019
Integration Guide
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58
Vendor Name:
Carrier
Product Names:
RTU Open
Product Model Number:
RTU Open
Protocol Description:
N2 is not a standard protocol, but one that was created by Johnson Controls, Inc. that has been made open and
available to the public. The speed of N2 network is limited to only 9600 baud. The N2 slave address can be set
from 01 to 99.
Product Description:
The RTU Open is a factory-installed rooftop controller that is capable of speaking multiple protocols. The RTU Open
controller speaks the Johnson N2 Open Protocol as described in the
Metasys N2 System Protocol Specification
(for Vendors) document
, revision 6/13/96. Further details on the N2 supported implementation are described
below.
Communication Types: Baud
rates:
Data Bits:
Parity:
Stop Bits:
2-wire EIA-485
9600
8
None
1
Network Point Types:
Analog Inputs (AI)
Binary Inputs (BI)
Analog Outputs (AO)
Binary Outputs (BO)
Internal Floats (ADF)
Internal Integers (ADI)
Internal Bytes (BD)
Protocol Commands:
Identify Device Type
Sync Time
Poll Without Acknowledge
Poll With Acknowledge
Read Analog Input
Read Binary Input
Read Analog Output
Read Binary Output
Read Internal Parameter
Write Analog Input
Write Binary Input
Write Analog Output
Appendix D: Johnson N2 Protocol Implementation Conformance
Statement
