Data Tables, Read/Write

Use the Read function to select Data Table rows and read their data into PLC memory operands. Values are read from the Data Table into the operands that are linked to it in the Read function. Note that the number of rows read cannot exceed the number of rows that are in the Data Table.

Use the Write function to select PLC memory operands and read their data into Data Table rows.

Values are read from the PLC into the Data Table cells that are linked to it in the Write function.

Note that you provide a Start Address for the PLC memory operands; the Write function will take a vector of operands that will fit the number of rows in the Data Table.

A column in a Data Table is the source for the Read function. Values are read from the Data Table into the operands that are linked to it in the Read function, according to FIFO.

PLC operands are the source for the Write function. Values are read into the Data Table cells that are linked to it in the Write function. Values are read from the operands into the Data Table according to FIFO.

The Read Direct operation copies data from the data tables into a vector of registers within the controller.

1. Select Direct: Read from the Data Tables menu.

2. Place the function in the desired net.

3. Link the desired Operands and Addresses.

4. Operands A & B determine the data's destination --to where the data from the data table will be copied.
   Operand A: sets the register type for the target vector and the start register.
   Operand B: determines the offset, in registers, from the start register.
    

5. Operands C, D, & E determine the data's source --from where in the data table the data will be copied.
   Operand C: contains the start byte of the source vector within the data table.
   Operand D: determines the offset, in bytes, from the start register.
   Operand E: determines the length of the source vector.
   
   Note that the length is relative to the type of register linked to Operand A.  For example, if Operand A is linked to an MI and Operand E contains 5, 10 bytes of data will be copied from the data table into 5 MIs,  2 bytes into each MI.
   If Operand A is linked to a double register; ML or DW; and Operand E contains 2, 8 bytes of data will be copied into 2 double register.

Read Example

The Write operation copies data a vector of registers into the database.

1. Select Data Block Read from the Data Tables menu.

2. Place the function in the desired net.

3. Link the desired Operands and Addresses.

4. Operands A & B determine the data's source --from which registers the data will be copied.
   Operand A: sets the register type for the target vector and the start register.
   Operand B: determines the offset, in registers, from the start register.
    

5. Operands C, D, & E determine the data's destination--to where in the database the data will be written.
   Operand C: contains the start byte of the source vector within the database.
   Operand D: determines the offset, in bytes, from the start register.
   Operand E: determines the length of the source vector.
   
   Note that the length is relative to the type of register linked to Operand A.  For example, if Operand A is linked to an MI and Operand E contains 5, the data from 5 registers will be copied into 10 database bytes,  2 bytes per MI.
   If Operand A is linked to a double register; ML or DW; and Operand E contains 2, the data from 2 double registers will be copied into 8 database bytes, 4 bytes per ML or DW.

Write Example