|
<< Click to Display Table of Contents >>
Numerical Configuration |
Numerical configuration is performed using N and B parameters of I/O Tags, not using the Device and Item fields available in Elipse E3 or Power, which must be kept empty.
This configuration method must be used in Elipse SCADA and in legacy applications. In applications using newer products, such as Elipse E3, Elipse Power, or Elipse OPC Server, it is recommended to use String configuration.
I/O Tags configured numerically reference operations previously configured on configuration window.
As already explained on topic Operations Tab, this Driver supports other data types in addition to protocol's native data types. For this reason, the concept of Operation was created on this Driver.
On operations using Modbus functions that read and write bits, such as protocol functions 1, 5, and 15, this Driver always map binary values of each bit to Block Elements, where each Element represents the value of a specific bit.
Operations with eight-bit data types, such as the Byte data type, always imply, obviously, on reading at least two bytes, a 16-bit Modbus register. To prevent surprises, this Driver requires that eight-bit data writings be performed in pairs, that is, writing Blocks with an even number of Elements. These operations must be referenced using I/O Tag's N2/B2 parameters, as described later.
The following configuration applies to I/O Tag's N parameters, as well as to I/O Block Tag's B parameters.
•N1/B1: Address of a slave device (PLC) on the network (Slave Id). This address can vary from 1 (one) to 247 for Serial networks via Modbus RTU or vary from 0 (zero) to 255 for direct communication with Ethernet devices via Modbus TCP. For Serial mode, the ID with a value of 0 (zero) is reserved for Broadcast mode, sending a message to all slave devices (PLC) on the network. In Ethernet, in Modbus TCP mode, the address generally used is the IP address, but the Slave Id can still be used when the IP address references a gateway connected to a device network, usually an RS485 network, with Modbus RTU, using a gateway capable of performing a conversion from Modbus TCP to Modbus RTU
NOTE |
In Serial Modbus RTU, the Broadcast mode with N1 equal to 0 (zero) cannot perform readings, only writings. In this mode all devices on the network are addressed, receiving the written value and not returning any response, to avoid network conflicts. |
•N2/B2: Operation code. References an operation added on this Driver's configuration window. For more information, please check topic Operations Tab
•N3/B3: Additional parameter. This parameter is not generally used and can be kept in 0 (zero). It is only used in these situations:
•Modbus functions 20 and 21: For operations that use these functions for file access, the functions 20 and 21, the N3/B3 parameters specify a file to access.
•Use Bit Mask: For Tags referencing operations with the Use Bit Mask option enabled, the N3/B3 parameter specifies the number of the bit to access. For more information, please check topic Operations Tab.
•User-Defined Data Types: For operations that use structures, if the B3 parameter is greater than 0 (zero), it defines the return of an event-reported block array, by using a sequence of Tag's OnRead events. For more information, please check topic User-Defined Data Types.
•Gen SOE Special Function: For operations that use the Gen SOE special reading function, the N3/B3 parameter indicates the size of the linked table in the PLC or slave device memory, as the maximum number of supported events. For more information, please check topic Elipse Software's Generic SOE Reading Algorithm.
•N4/B4: Register, variable, or bit address on the slave device (PLC) to read or write, according to device's register map. For more information, please check device's documentation. It is important to correctly configure the Data Address Model Offset option. For more information, please check topic Modbus Tab and check if manufacturer's documentation does not use offsets used by old Modbus devices, known as Modbus Convention.
•Size/Index (Block Tags only): Each Block Element represents a data value of a type defined in the operation used, in the N2/B2 parameter. Notice that this protocol only supports Bit or Word types. Thus, if this operation selects the DWord type, 32-bit, for each Block Element, this Driver must read two consecutive registers from a device.
In addition to I/O Tags, that is, Tags referring to operations, there are also special Tags to execute specific functions of this Driver. These Tags are described on topic Configuring Special Tags.