133 • HRVS-DN Communication (ModBus Protocol)
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16.6
List of Functions Supported By The HRVS-DN
Function Modbus Name
Use in HRVS-DN
01 Read Coil Status Read discrete commands status.
02 Read Input Status
Read discrete inputs status.
03 Read Holding Registers. Read parameter settings.
Read actual data (for Modbus Plus users).
04 Read Input Registers.
Read actual data.
05 Force Single Coil.
Force one discrete command.
06 Preset Single Register.
Write one parameter setting.
08 Diagnostics.
Loopback diagnostics.
15 Force Multiple Coils.
Force discrete commands.
16
Force Multiple Registers Write parameter setting
control commands
DATA
Data field includes information transferred to and from the HRVS-DN. The specific data format is changed with
Function. When Word data parameters are transmitted, High Byte is transmitted first, followed by the Low
Byte.
CRC
The CRC (Cyclic Redundancy Check) two bytes (16 bit) are used to check the bytes of the entire frame.
It is generated in the master device and transmitted as the last two bytes of the frame (Low byte is appended
first, followed by the High byte). The slave device regenerates the CRC bytes and compares it to the CRC
bytes received. If the CRC bytes are not identical, the frame is flushed and no response is transmitted to the
master.
HRVS-DN MEMORY ORGANIZATION
The HRVS-DN memory is organized according to the common Modbus addresses as follows:
