LonTalk communication protocol
Supported device types and versions
Communication line configuration
Communication line protocol parameters
Communication station configuration
Communication station parameters
I/O tag configuration
Literature
Changes and modifications
Document revisions
Supported device types and versions
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Communication line configuration dialog box - tab Protocol parameters.
They influence some optional protocol parameters. The following line parameters can be set:
Tab 1
| Parameter
| Meaning
| Unit
| Default value |
|---|
| High level of the communication tracing. It shows the read values of I/O tags and other debug information. | YES/NO | NO |
| A time interval. After it passes, a re-open action over the interface will be done. 0 (zero) disables this function. | min | 0 |
| Kotva |
|---|
| komunikacna_stanica |
|---|
| komunikacna_stanica |
|---|
|
Communication station configuration
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Communication protocol: Echelon LonTalk.
The station address (node) consists of the required address parameters (i.e. "Subnet/Node Addressing"):
- Domain is a domain number (0 or 1).
- Subnet specifies a network ID (0 up to 255), as a decimal number.
- Node is a node number in the network (0 up to 127), as a decimal number.
Neuron ID is an optional address parameter. If it is defined, this address executes the polling of the network variables of node. Neuron ID address is in the hexadecimal form.
If it is necessary to send a network variable value with another address type than "Subnet/Node Addressing", you can configure Group or Broadcast address parameters.
- "Group Addressing" parameters:
- ID specifies a group ID in the domain (the decimal number ranging from 0 to 255).
- Member is a member ID of a target node in this group (the decimal number ranging form 0 to 63).
- Size is a group size (2 up to 64). The group size is unlimited when you set 0 (zero).
- "Broadcast Addressing" parameters:
- Subnet defines a network ID to which a broadcast message is sent. Set a required value Domain.
- Backlog is an estimated number of ACKD responses or request/response messages.
Parameter description from the literature 1: This field specifies an estimate of the channel backlog that would be created by an acknowledged or request/response message broadcast using this address. It should be set to the expected number of acknowledgements or responses. For example, this might be the worst case number of nodes expected to respond to a message on a channel. If this is unknown, this field can be set to zero in which case a backlog of fifteen is assumed.
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They have effect on some optional protocol parameters. The following station protocol parameters can be defined:
Table 1
| Full name | Meaning | Unit | Default value |
|---|
| Value of the parameter is written into the address array SendAddrDtl when the packets "Poll request" and "Write NV value" are sent. See the Note 1.
Parameter description from the literature 1: This field specifies the time interval between repetitions of an outgoing message when unacknowledged–repeated service is used. | - | 3 |
| Value of the parameter is written into the address array SendAddrDtl when packets "Poll request" and "Write NV value" are sent. See the Note 1.
Parameter description from the literature 1: This field specifies the number of retries for acknowledged, request/response, or unacknowledged–repeated service (0–15). The maximum number of messages sent is one more than this number. | - | 1 |
| Value of the parameter is written into the address array SendAddrDtl when packets "Poll request" and "Write NV value" are sent. See the Note 1.
Parameter description from the literature 1: This field specifies the time interval between retries when acknowledged or request/response service is used. The transaction retry timer is restarted when each attempt is made, and also when any acknowledgement or response (except for the last one) is received. For request/response service, the requesting node should take into account the delay necessary for the application to respond when setting the transaction timer. | - | 3 |
| Timeout for receiving the respond on the polling demand. Total time is tx_timer * retry + Response timeout. | ms | 500 |
| Timeout for receiving the confirmation of sent packet with a new value. Total time is tx_timer * retry + WAT. | ms | 1500 |
| If its value is YES, writing new values into the network do not wait for confirmation (with Writte ACK Timeout). They are immediately acknowledged as received. | YES/NO | YES |
Skip Reading after Failed Polling | If the value is YES, the reading of I/O tag values is stopped by the polling on the given station (node). It helps to speed up the value reading form the network variables when some nodes do not communicate (they are switch off). The communication is not delayed because of waiting on the responses of polling from non-functional node. The polling always starts properly but after the first error in reading by polling the reading of remaining network variable interrupted and next node is read. | YES/NO | NO |
The parameters
rpt_timer,
retry and
tx_timer can get values ranging from 0 to 15. Conversion table for times in milliseconds is stated in the document
LonWorks communication line configuration and in the
literature nr.1.
I/O tag configuration
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I/O tag address consist of:
- Selector - required parameter - basic identifier of the I/O tag within the range of 0..16383, as a decimal number or as a hexadecimal number with a prefix #, e.g. #3A.
- Type - value type of the network variable, required, options are: SNVT, ushort (1 byte, unsigned), short (1 byte, signed), ulong (2 bytes, unsigned), long (2 bytes, signed), float_type (4 bytes IEEE-754), analInp (a special format Weidmuller), long_4 (4 bytes, signed) or struct (1 and more bytes).
- SNVT - if you select the SVNT type in the parameter Type, then you must define a SVNT type number (0..255), as a decimal number.
- Bit - if you select the I/O tag type either Di or Dout, you can define a number of the bit within the frame of a 2-byte value word (0..15).
- Poll - allows the network variable polling. Polling is performed within the interval according to the station time parameters (polling parameters).
- Priority - indicates a higher priority for writing and polling (in terms of LonWorks network communication).
- Authentication - enables the authentication for the network variable writing and polling.
- Service - for output I/O tags, you must define a type of the network communication for writing (ACKD, UNACKD_RPT, UNACKD); standard secured transmission type ACKD.
Value type
structThis type enables to split data of any length to the bytes or bits. You must set an index 'byte' (numbered from 1) and eventually the bit number (0 up to 7) for I/O tags of Di type. the separated bytes are interpreted as non-signed numbers from 0 up to 255.
Note: Using the nodeutil utility it is possible to:
- Connect to LON device:
a) either by entering the hexadecimal 6-byte Neuron ID via menu "A -- (A)dd device to list."
b) or by pressing the service pin on the LON device, which causes the message "Received an ID message from device x" to apper.
Then select the appropriate device via menu "G -- (G)o to device menu...." . - Read configuration information via menu "C -- Application (C)onfiguration structures.
- Read the list of network variables via menu "N -- (N)etwork Variable configuration table.".
The list contains indexes of variables, their selectors, direction (in/out) and other parameters. - Save the list of network variables in HC format to the file via menu "L – (L)ist network variables."
- Save the XIF file to the interface file via menu "X -- Create device interface ((X)IF) file."
Additional information about the LON device and individual variables can be read from the interface file.
Literature
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- Ver. 1.0 – October 27th, 2000 – Creating of document.
- Ver. 1.1 - January 25th, 2011 - Updating of document.
- Ver. 1.2 - October 25th, 2012 - Updating of document.
- Ver. 1.3 - December 5th, 2019 - Hexadecimal notation of Selector, a note about nodeutil.
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