CC-Link IE Field Basic is an ethernet based industrial communication stack. The standards are maintained by the CC Link Partners Association (CLPA). Since the protocol is defined in the application layer no special hardware is required.
Central Concepts
SLMP
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SLMP (Seamless Messaging Protocol) is a protocol used to implement communication between applications seamlessly without awareness of the network hierarchy and boundaries. It is often used in communication between the CC-Link family network and other general-purpose Ethernet devices.
SLMP messages are defined as payload, using a lower-level network service such as TCP/IP, UDP or CC Link IE TSN/ CC Link IE Field Basic as transport layer. In the port CC Link IE Field Basic implementation, SLMP is already contained.
The CC Link IS Field Basic stack uses SLMP messages only for slave device identification and IP set operations. Therefore, only these two types of messages must be supported.
Link Devices
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The data that is transferred, is locally organized in so-called link devices. These differentiate by direction and by data type. The size of the link devices per such called station is constant.
Name | Size per station | Direction | Content |
|
RX | 64 bits (8 bytes) | To Master | Input | Digital, “Points” |
RY | 64 bits (8 bytes) | To Remote Station | Output | Digital, “Points” |
RWr | 32 words (64 bytes) | To Master | Input | Compound Data, “Words” |
RWw | 32 words (64 bytes) | To Remote Station | Output | Compound Data, “Words” |
Table 7: Overview of link devices
Using the GOAL CC-Link IE Field Basic slave stack it is possible to setup a slave occupying 1 to 16 stations. Each station can be interpreted as a physical or virtual participant of the CC-Link IE Field Basic network. To each of the stations there is a fixed amount of I/O data with fixed size, called Link Devices. I.e., to exchange more I/O data the slave may occupy more stations.
This leads to 72 bytes process data for each direction per slave station, leading up to a maximum of 1152 bytes per direction for a GOAL CC-Link IE Field Basic slave.
For a slave containing more than one station the link devices sizes are multiples of the given sizes. E.g., a slave occupying two stations has 16 bytes RY data.
The meaning of each bit within the Link Devices is application specific, i.e., the protocol specifies the size of each Link device, but the application decides which data points are used.