Figure 1: Modbus Write Point Function Block |
Figure 2: Modbus Write Point Property Sheet |
Input
Input Name |
Description |
In |
Writes to the Modbus holding register Numeric: 32-Bit floating point value (float), "null" = Ignore |
n:child |
Shows the relation to the corresponding Modbus device in the wiresheet. |
Table 1: Inputs of Modbus Write Function
Output
Output Name |
Description |
Out |
Modbus Output 32-Bit value, Null (This value type can be Boolean, Integer, Unsigned Integer or float) Boolean- This value type represents the data in two states viz. true or false, on or off etc. This data is stored in a 32-Bit (4 byte) register ranging from 0-1. Signed Integer or Integer- A signed 32-bit integer, is a variable type taking up 4 bytes in memory, with the ability to hold a value ranging from -2147483648 to 2147483647. The signed part of the integer refers to its ability to represent both positive and negative values. Unsigned Integer- A 32-bit unsigned integer can hold a value from 0 to 4294967295. Float- A float is a 32-bit single precision value, sometimes called real. With a floating type value, very small and large numbers are possible. When the system is not able to read from the register it will display output as null. |
Outcause |
Exception Code/ Cause Numeric: 32-bit value Outcause Enums: 0: No error 1: Illegal register address 2: Illegal argument 3: Porting layer error 4: Insufficient resources 5: I/O Error 6: Protocol stack In Illegal state 7: Retry I/O operation 8: Timeout error occurred 10: Illegal function exception 11: Illegal data address 12: Illegal data value 13: Slave device failure 14: Slave acknowledge 15: Slave device busy 16: Memory parity error 17: Gateway path unavailable 18: Gateway target device failed to respond 100: Others 255: Data Not Ready (When the register is in initial configuration). |
Table 2: Outputs of Modbus Write Function
Parameter
Parameter Name |
Description |
Write Point Type |
Modbus Slave Register Type Enumerated: 1-4 Default: 1 5: Write Single Coil (FC-5) 6: Write Single Register (FC-6) 15: Write Coils (FC-15) 16: Write Multiple Registers (FC-16) |
Device Address |
ModBus device address (to which this coil belongs to) Device Address is unique across modbus network. |
Byte Order |
It determines the byte order to be considered when communicating with the modbus registers. 0: Big Endian (e.g Byte1, Byte 2, Byte 3, Byte 4 for a 32-bit integer value) - For Register and for Word (2 register read), you get MSB first from Modbus device. 1: Little Endian (e.g Byte 2, Byte 1 or Byte 4, Byte 3, Byte 2, Byte 1) - For Register and for Word, you get LSB (2 register read) first from Modbus device. 2: Little Endian with word swap (e.g. Byte 2, Byte 1, Byte 4, Byte 3) - For Register, you get LSB first and for Word (2 register read), you get MSB first from Modbus device. 3: Big Endian with word swap (e.g. Byte 3, Byte 4, Byte 1, Byte 2) - For Register, you get MSB first and for Word (2 register read), you get LSB first from Modbus device. |
Significant Change |
Difference between the current value of In and last transmitted value, that will cause the new value to be sent to the Modbus device. Numeric: 32-Bit floating point value (float) Default: 0. |
Data Format |
Enumerated; Range: 0-7; Default:0 0: Single Bit 1: Int16 2: uint16 3: int32 4: uint32 5: float (4-byte, single precision) |
Operation Mode |
Enumerated; Range: 1-2; Default: 2-PeriodicSending 1: Do Not Send 2: Periodic Sending |
Out Save |
Master Sync Enabled : If you set it to "true" the last output will be set as output for one cycle after the controller restarts. The application can use it to return to the same state before the controller restart. Out: To enable or disable the Out feature. Out Cause:To enable or disable the Out Cause feature. |
Table 3: Parameters of Modbus Write Function
Follow the below steps to add Modbus Write Point:
Double-click on the Modbus device to view below Modbus Device Configuration View screen
Select Write Points tab and click Add
Figure 3: Modbus Device Configuration Screen
Enter the following detail like the Point name, Write Point address, Write Point Type, and Data Format in the Modbus Write Point window. In the below example, for Loytec Thermostat and its Modbus details.
Click OK.
Figure 5: Example- Modbus Write Device
Refer to General Description for general information about IRMN4 Function Blocks.