The purpose of this Function Block (FB) is to simplify the immediate configuration of the CJ1W-CORT21 card for communication devices with CAN-Open. The Function Block sets the buffer for transmission and reception, setting the ID and the transmission method in a way that is transparent to the user. Instead of using complex Cmnd instructions Cmnd just three tables will show the necessary parameters.

The card can send messages with a 11Bit identifier directly, with the command Cmnd 2907, or via a buffer. In this second case it is also possible to set the method for sending messages. You can choose between three modes, with trigger bits, at intervals, or on the status change of the field data.

The reception of CAN messages is done solely through the buffer, of which a maximum of 280 buffers can be set for reception. For each buffer we can match a different ID.
The establishment of buffer areas, the building blocks to be sent and the definition of filters receipt, is affected by FINS commands addressed to the card CORT21. For sending commands to the card you must use the instructions Cmnd.

Structure of the buffer CORT21

A maximum of 280 buffers for both the input and output can be defined within the memory of the PLC. Each buffer consists of 5 words, the first word contains the length of data field in bytes (0 to 8), the next 4 words represent the data field with two bytes per word. It is also possible to select the order of bytes within the word between Big Endian (least significant byte precedes the most significant byte) which is the default and Little Endian which is more suited to the internal representation in the Omron PLC.

Used Variables

Admission

Exit

Table for memory allocation

m = DM allocated first to the table (Buffer_table)

Transmission Buffer table definition

k=first word of the definition table of the transmission buffer (Send_table)

....

k+3 × buffer number_TX - 1
The three words are repeated for each buffer 

Receiving Buffer table definition

z = first word of the definition table of the receiving buffer (Recv_table)

...

z + buffer number-1

Transmission Buffer

T = first word in the transmission buffer as specified in word m +1 me.

Trigger for the transmission
For each buffer transmission there is a corresponding bit in the Trigger, the Bit 0 of the first word matches buffer 0, the next bit buffer 1 and so on. If you have already selected how you want to send 1, resulting in a Bit On, the trigger will send the message stored in the buffer's corresponding transmission. CORT21 will replace the Bit Off used.

R = first word in the transmission buffer as specified in word m +2 and m +3

Receiving Buffer

U = first word in the receiving buffer as specified in word m +5 and m +6.

Receipt Flag

Each receiving buffer has a flag, Bit 0 of the first word matches buffer 0, the next time the buffer 1 and so on.
The status of the flag has the following meanings:
ON: It has received a message with the ID set to the last I / O refresh
OFF: It has not received any message within the defined ID. 

S = first word in the receiving buffer as specified in word m +7 m +8.

Use
The card can only be configured when the CAN interface is not active. If you try to configure the card while it is in any other state, the configuration will be ignored and it will activate the output error of the block function. This situation corresponds to the error code 0401 hex. 
The status of the card can be changed on the Bit 04 of the first word on the Bus CPU module (eg if the card has the number of units 0, the corresponding bit is 1500.04).

n = 1500 + 25 × Unit number

The configuration is maintained until the PLC is shutdown. Each time you need to configure the card you activate the CAN interface. If you do not want to use the communication buffer it is necessary to configure it, setting the number of buffers for transmission to 0.
To start the CAN network you must then:
1. Configure the CORT21 card using the blocking function Set_buffers " 
2. Choose a Bit On status for the CAN 
3. Send to all nodes of the network the activation signal for the operating condition (operational state), for this function you can use the lock function Start_all_nodes "

Activation of the Function Block must be done with the bit always On.  Launching the configuration is done on the rising edge of the bit related to "execute". Before starting the configuration it is necessary to prepare the tables for configuration. MOV instructions can be used for doing so. You can also use the editor of the CX-Programmer and transfer data on the PLC. For the input parameters of the block may be used instead of a constant. 

Completing the configuration will take several scans, the number of them depends on the number of buffers configured. During processing the exit "Busy" term is On. Once completed the "Busy" Bit switches to off and, if there are no errors,  The "Done."  Bit switches on. In case of error, the "Done" bit will not come on and instead the "Error" bit will open with Exit "ERROR_CODE" returning the error code of the last operation performed. For error codes refer to the manual card CORT21.

Correct Configuration

Incorrect Configuration

Starting the CAN Open network (FB Start_all_nodes)

All CAN Open devices are based in a state called "Pre operational state", in this mode, the devices are waiting for configuration and data exchange network. To start the network and start the data exchange it is necessary to send a message that orders CAN Open nodes to move to the "Operation" state. The operational nodes exchange data over the network and can not accept a new configuration. The function block Start_all_nodes sends a message on the network. Operating is very simple, just specify the Unit Number tab of the PLC and CAN lead to the Input On "start_comm".

Variables used
Admission

Exit

Application example
The configuration considered in this example includes a CJ1 PLC CORT21 card set to 0 units, two inverter 3G3MV with PCORT interface, a module I / O to 16 digital inputs and a module for 16 digital outputs.

For defining the buffer it is necessary to derive the CAN identifiers used in the exchange data. Open devices in the CAN data are organized into objects, to send and / or receive data, the device relies on the special item the PDO (Process Data Object); PDO exists for the transmission of data, TPDO for receiving data, and the RPDO. TPDO and RPDO are assigned an identifier called COB-ID (Communication Object ID) and one or more objects contain the data I / O of the slave. Each PDO can send or receive a maximum of 8 bytes. All devices have CAN Open PDO defaulting to the default COB-ID. The CAN Open protocol defines a minimum set of two TPDO and two RPDO. Mapping of default and related PDO COB-ID can be derived from the documentation accompanying the device. Each manufacturer is free to add additional PDO to the default configuration.

Default mapping of an I / O device.
The documentation can be found in the following IDs

Inverter 3G3MV with PCORT21

Input module to 16 points

Output module to 16 points

Note: This will not be used as the mode of the mailbox Inverter

Network Configuration

Inverter 1 Node 1
Inverter 2 Node 2
16in Card Node 7
16out Card Node 10
Monitoring data of the inverter will be operated on the status change, while the speed will be sent using trigger bits. The slave output is updated every 100ms.

All Data

Contents of the Buffer configuration table

Contents of the transmission buffer definition table

Contents of the receive buffer definition table

Test Program