EC-Net-AX - Lonworks Binding Help for Distech Controls ECL, ECP, ECC Controllers

EC-Net-AX - Lonworks Binding Help for Distech Controls ECL, ECP, ECC Controllers

Binding is a process of one-way or two-way communication (depending on the type) between a sender and receiver to send an updated value and/or mode. The internal point initiates the communication by sending an updated current value/or mode to the control point. For NVOs, this method can be used for medium to large scale networks since, generally, updates are sent only when the value and/or mode of the internal point changes in accordance to the MaxSendTime and MinSendTime values defined in the controller.

NCIs cannot be bound: When an NCI is “polled”, the internal control point sends out ONLY one request for an update when it becomes subscribed. This can either be initiated directly by the user or, if the NCI is in a graphics (Px) page, it is initiated when the page is first opened. An NCI is generally used as part of a graphics (Px) page where one value and/or mode update is sufficient and not when it is part of a control logic sequence, alarm sequence or being logged where regular automatic updates are often required.

There are 4 types of bindings or Service/Link Types: Standard, Reliable, Critical, and Authenticated. Link Types can be selected under the Proxy Ext parameter of each of the respective NVOs that are linked (see Figure 1). If the Service Types of many NVOs are to be selected at the same time, use the Lon Link Manager. Right-click BcpLonNetwork in the in the Nav tree to access the Lon Link Manager.

 

 

Figure 1 Defining the Service Type through the Lon Link Manager

 

Parameter

Description

Standard

Is the least reliable, yet often most widely-used (also known as unacknowledged). This is the default service type for a EC‑Net binding. With this service, the message is sent one time and no response is expected. This service is typically used when the highest level of network performance is needed, network bandwidth is limited, and the application is not sensitive to the loss of messages.

Reliable

Is recommended for messaging that has been classified as important— if there is a specific need to know that a status has changed (also known as unacknowledged/repeated). Reliable messaging sends a message three times. The srcDevice sends each message three times, and if the targetDevice receives the message, it simply throws subsequent messages away.

Critical

Means that the targetDevice must acknowledge the fact that it received a message (also known as acknowledged). The srcDevice continues to send the message until the targetDevice acknowledges receipt of that message. You are limited to the number of bindings that can be defined as critical, because it taxes the system, and often causes communications issues (by loading down the network with message verification traffic).

Authenticated

Is a security service reserved for secure messaging. When using authentication, the srcDevice must identify itself to the targetDevice, and vice-versa. This service is rarely used, and only in instances where messaging must be secure.

If you set Priority in combination with any of the message service types, upon a bind, the Priority flag is set in the network variable’s Nv Config Data.

NOTE  

It is very important to change the default MaxSendTime and MinSendTime of programmable controllers in medium to large scale networks. For example, they should be changed to MaxSendTime = 300s and MinSendTime = 15s.

Once the links have been created, remove any unnecessary control points to reduce the amount of memory resources needed by using the Trim feature.

 

 

Types of Points

There are two types of controller points that can be created in EC‑Net.

 

Parameter

Description

     

Standard EC‑Net network variable.

     

Controller internal points are special control points that allow for the control of internal parameters. These internal points are created through the Create Points feature.

This icon can be identified by the black dot in its center, whereas the standard EC‑Net network variable icon has no dot in the center.

 

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