Johnson Controls N2-Bus protocol
Supported device types and versions
Communication line configuration
Communication station configuration
Station parameters
I/O tag configuration
Time Schedules configuration
Literature
Changes and modifications
Document revisions
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- Categories of communication line: Serial, SerialOverUDP Device Redundant, TCP-IP/TCP.
- Transmission parameters N2 Bus, usually set on to 9600 Baud, 8 data bits, no parity, 1 stop bit.
Note: on TCP-IP/TCP line, multiple host names separated by comma/semicolon can be defined, to connect to multiple devices in round-robin fashion.
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- Communication protocol: Johnson Controls N2-Bus.
- Address of station on N2 Bus is the number in the range of 1 to 255, the address 0 is reserved.
- Reading values of objects on station is executed periodically according to time parameters "Polling parameters".
- The synchronization of real time can be activated - check the Enable parameter in "Synchronization period" section and set the period, which defines a period of recording a real time.
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The configuration dialog box - Parameters tab.
The parameters influence some optional parameters of protocol. There can be defined the following parameters of station protocol:
Table 1
| Parameter | Meaning | Unit | Default value | ||||||
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| Delay between reading the responses until it is completed. | millisec | 100 millisec | ||||||
| The first waiting for a response after sending a call. | millisec | 200 millisec | ||||||
| Delay between retry calls if a communication error occurs. | millisec | 500 millisec | ||||||
| Number of retry response reading until it is completed. | - | 10 | ||||||
| Number of retry calls when error in communication occurs. | 1 .. 32 | 2 | ||||||
| Enables the detailed debug information about values of I/O tags that were obtained by polling. | YES/NO | NO |
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Used I/O tags: Ai, Ao, Ci, Co, Di, Dout.
The address of I/O tag can define in two formats:
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Modul.Tag
Where Modul is a name of module and Tag is name of tag within a module. List of items is based on the documentation DX-9100 Configuration Guide, Appendix B. Since this is a large list of the static items, there is prepared "Object Browser" dialog window, where you may find the particular object. In the "Item Address" section click the button next to the "Item" field.
The following window opens:
The left part of window contains the list of modules. After clicking the particular module, the list of tags that belong to this module are displayed in the right part of window.
Parameters of items:
Tag: Name of tag.
Description: Short description of item.
Access: Access level (R - read-only, R/W - read and write, CNF - read and write, the configuration parameter is recorded into EEPROM).
Type: Value type of item (see also here).
Address: Physical address of item that is used for reading/writing. It is calculated from the starting address of module and offset tag (in hexadecimal format). The bit number (1 up to 32) of the addresses of binary items is placed after dot.
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#Typ.Addr[.Bit]
Where:
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| Value type | Range, value interpretation |
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| U8 | 8 bits unsigned (JC tagging 1 Byte) |
| U16 | 16 bits unsigned (JC tagging 2 Byte) |
| U32 | 32 bits unsigned (JC tagging 4 Bytes) |
| I8 | 8 bits signed (JC tagging 1 Byte Int) |
| I16 | 16 bits signed (JC tagging 2 Byte Int) |
| FP16 alebo N | 16 bits floating point in Johnson Controls format (JC tagging Number) |
| CONN | Connection - interpreted as 16 bits unsigned |
| DST | Destination - interpreted as 16 bits unsigned |
Address is the address of item in decimal format.
Bit is a bit number. Optional parameter, it is important only for binary items, when the particular bit is extracted form the value of whole item (for U8, U16 or U32 items).
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