Modbus Item Syntax |
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The Modbus item syntax is set up as shown below:
If the data type is BOOL, the bit number is required:
The following item syntax allows to address a different UnitID as set up at the connection parameters:
Legend: <> mandatory [ ] optional [UnitID.]The UnitId item syntax is specified for an item with the literals "ID" followed by a number and a dot. The range is 0 - 255. If the UnitID is not present in the Itemsyntax, the parameterized UnitID is transferred to the PLC. Samples: Id1.40001 Id2.R2 Id3.S5.30 <Area>
1 BIT-oriented means that one bit is addressed for each physical address. WORD-oriented means that one word (16 bits) is addressed for each physical address. 2 Entry of the start address is octal and the numbers 8 and 9 are invalid characters. Internally, the address is handled decimally and must be considered for logger and status entries.
Areas can either be addressed via the above stated alphabetic sequence or via a number. This means that a discrete input can be addressed by the abbreviation "E" the same as with the number "1", discrete outputs by letter "O" or number 0, Input registers by "IR" or "3", Registers by "R" or "4". <Data type>
1 Diskrete Inputs and Outputs are one single bit in the PLC. When reading from Register or Input Registers, the whole register is read and the bit is extracted. Note: Writing of individual bits in the register and input register area is possible if the writing of bits in the word is activated in the configuration of the connection. The entire register is then read, the bit is set or deleted and the register is written back again. 2 The suffix SWAP is possible for a string to give the bytes the correct order. For the other data types all bytes are changed in the order. 3 KA Suffix is not possible with string arrays <Start address>The start address specifies the address starting at which read or write accesses begins. Example: ER5 -> Input Register 5 O12 -> Output 12 <.Bit number>The bit number must always be specified when the data type is BOOL! Example: HRX5.2: Bit 2 of holding register 5 [.Array size]Arrays are created to combine several units of one data type together in one field. Example: HRD5.3 For more information on arrays, see also Arrays. [Suffix]A value can be represented in another format with the aid of a suffix. For more information on suffixes, see also Suffixes.
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