Converteam GEMTEQ I/O GEM80, Техническое руководство

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GEMTEQ I/O 2. Introduction to CAN Networks
Slave GEMTEQ modules have a fixed size and number of PDO’s assigned to each module.
There are 16 C/D tables (a maximum of 4 transmit and receive PDO’s) per node ID.
Any configuration data for the module is included within the 16 words of output PDO data, the
GEMTEQ network does not use SDO’s to configure slave modules.
To reduce the network traffic on the GEMTEQ link, data is only normally transmitted when data
changes. A slave input module will transmit data to the GEMTEQ scanner module when it detects
an input change. The scanner will transmit data to a slave output module when it detects that the
output data PDO has changed within the scanner module.
2.2 DATA EXCHANGE TO THE HOST CONTROLLER
The GEMCAN I/O Scanner module resides in the host PLC and provides an interface between
the PLC and the module’s two CAN communication ports. Typically before the host PLC Ladder
Scan, data is transferred between the GEMCAN I/O Scanner module and the host Data Table
memory. At the end of the host Ladder Scan, data is transferred from the host Data Table
memory to the GEMCAN I/O Scanner for transmission on the CAN network. Transfer depends on
the scanner sub mode as detailed in section 4.2.4.2.
GEMC AN I/O Scan n er
Mo d u le 1
Host GEM80 Controller
Ladder
Scan
Data
Table
Memory
2
3
4
1 5
Po rt B Po rt A
Figure 2-2 GEMCAN I/O Scanner Data Exchange with Host PLC
1 - Slave devices transmit their data to the GEMCAN I/O Scanner, as and
when the Input data from the plant changes
2 - At the beginning of the Ladder Scan, new Input data is transferred from the
GEMCAN I/O Scanner to the Host PLC Data Table memory
3 - During the Ladder Scan data is read from/ written to the Data Table
memory
4 - At the end of the Ladder Scan, Output data is transferred from the Data
Table memory, to the GEMCAN I/O Scanner.
5 - If the Output data has changed for a given Slave device, then new Output
data is transmitted to that Slave via the CAN network
GEMTEQ I/O Technical Manual (T2031En) Page 2-2
Rev.02 (10/10)