Communications Functions
This section describes the general-purpose serial communications functions (Modbus
communication).
8-1
Communications Specifications ....................................................................... 8-3
8-2
RS485 Terminal Arrangement and Connection ............................................... 8-4
8-3
Modbus Communication Parameters............................................................... 8-5
8-4
Modbus Communication Protocol.................................................................... 8-7
8-4-1 Message Configuration ........................................................................................ 8-7
8-4-2 Required Communications Time ......................................................................... 8-9
8-4-3 Normal Response ................................................................................................ 8-9
8-4-4 Abnormal Response ............................................................................................ 8-9
8-4-5 No Response .................................................................................................... 8-10
8-5
Explanation of Each Function Code ............................................................... 8-11
8-5-1 Read Coil Status [01 hex] .................................................................................. 8-11
8-5-2 Read from Holding Register [03 hex] ................................................................ 8-12
8-5-3 Write to Coil [05 hex] ......................................................................................... 8-13
8-5-4 Write to Holding Register [06 hex] ..................................................................... 8-14
8-5-5 Loop-back Test [08 hex] .................................................................................... 8-15
8-5-6 Write to Multiple Coils [0F hex] .......................................................................... 8-16
8-5-7 Write to Multiple Holding Registers [10 hex] ...................................................... 8-18
8-5-8 Read/Write from/to Multiple Holding Registers [17h] ......................................... 8-19
8-5-9 Exception Response ......................................................................................... 8-20
8-6
Saving a Change to Holding Register (Enter Command) ............................. 8-21
8-6-1 How to Issue Enter Command .......................................................................... 8-21
8-6-2 EEPROM Write Mode ........................................................................................ 8-23
8-7
Modbus Mapping Function ............................................................................. 8-24
8-7-1 Operation of Modbus Mapping Function ........................................................... 8-24
8-7-2 Modbus Mapping Function Settings .................................................................. 8-25
8-7-3 Compressed Single-word Registers .................................................................. 8-26
8-7-4 Troubleshooting for Modbus Mapping Function ................................................. 8-28
8-7-5 Endian Function ................................................................................................ 8-29
8-8
Co-inverter Communication ............................................................................ 8-31
8-8-1 Co-inverter Communication Parameters ........................................................... 8-32
8-8-2 Co-inverter Communication Settings ................................................................. 8-35
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