Modbus Server Demo

Overview

RAPIDSEA supports Modbus protocol as explained in the Modbus protocol page. This stack will be used by the customer according to their custom logic. This stack contains serial configuration and IP configuration.

The below diagram captures the high level flow of Modbus server

Response Functions

Function	Description
Read Coil Status (0x01) response	The coil status response message packed as one bit for one coil ( 1 -on and 0- off) of the digital outputs according to the client starting address
Read Input Status (0x02) response	The input status response message packed as one bit for one register ( 1 -on and 0- off) of the digital inputs according to the client starting address.
Read Holding Register (0x03) response	The Holding register response message packed as two bytes (high and low bytes ) for one register of the analog outputs according to the client starting address.
Read Input Register (0x04) response	The input register response message packed as two bytes (high and low bytes ) for one register of the analog inputs according to the client starting address
Write Single Coil (0x05) response	The single coil response message is simply as the echo of the request. If the request has FF00H forces the coil to be turned on and 0000H forces the coil to be turned off.
Write Single Holding (0x06) response	The single holding register response message is packed as simply as the echo of the request. The value to be written is packed as two bytes (high and low).
Write Multiple Coil (0x0F) response	The multiple coils message response is packed as no of coils to be written ( high and low bytes) of the digital output.
Write Multiple Holding (0x10) response	The multiple holding message response is packed as no of registers to be written ( high and low bytes) of the analog output.

Modbus Running Example

Refer to the Supported Platforms page to setup your environmental setup and follow further.

Modbus smart meter demo running example in modbus server application

Modbus smart meter functions

Register Address	Size	R/W	Variable name	Data type	Value/range	Functionality
03001	1 bit	RW	Cut-off Phase 1	uint8	0 to 1	I1 stops incrementing
03002	1 bit	RW	Cut-off Phase 2	uint8	0 to 1	I2 stops incrementing
03003	1 bit	RW	Cut-off Phase 3	uint8	0 to 1	I3 stops incrementing
03004	1 bit	RW	Reset Monthly Consumption	uint8	0 to 1	Reset the monthly consumption to 0
14001	1 bit	R	Current1 Alarm Level	uint8	0 to 1	Indicate current1 alarm level status
14002	1 bit	R	Current2 Alarm Level	uint8	0 to 1	Indicate current2 alarm level status
14003	1 bit	R	Current3 Alarm Level	uint8	0 to 1	Indicate current3 alarm level status
31001-31008	16	R	Meter Name	UTF8	“RAPIDSEA EM”	Manufacturer Name
31009-31010	4	R	Serial Number	uint32	0x10203199	Serial number of the meter
31011	2	R	Number of Phases	uint16	0x3	Number of Phases
31012-31013	4	R	I1 Current	float32	0 to 5.5	Rolls from 0 to 5.5 at a rate of 0.1 per second
31014-31015	4	R	I2 Current	float32	0 to 5.5	Rolls from 0 to 5.5 at a rate of 0.23 per second
31016-31017	4	R	I3 Current	float32	0 to 5.5	Rolls from 0 to 5.5 at a rate of 0.08 per second
42001-42002	4	RW	I1 Alarm Level	float32	0.0 to 5.5	Raises alarm in Current1 Alarm level register
42003-42004	4	RW	I2 Alarm Level	float32	0.0 to 5.5	Raises alarm in Current2 Alarm level register.
42005-42006	4	RW	I3 Alarm Level	float32	0.0 to 5.5	Raises alarm in Current3 Alarm level register.
42007-42008	4	RW	Baud Rate	uint32	9600/14400/19200/38400/57600/115200	Serial Configuration of Baud-rate
42009	2	RW	Parity	int16	N(0)/O(-1) /E(1)	Serial Configuration of parity
42010	2	RW	Slave Address	uint16	1 to 255	Modbus Slave Address
42011-42018	16	RW	Phase Name	UTF8	Default value : “RAPIDSEA PHASE1”	Phase1 Name
42019-42022	8	RW	Tariff Rate	double	0.0 to 5.5	Cost Per Energy Unit
42023-42024	4	RW	Monthly Consumption	int32	Default value : -10. Range -10 to 10	Net Energy consumption. Increments 1 per 10 seconds
42025-42028	8	R	Cost	uint64	eg: ( 1.1(Tariff rate) * -10 (Consumption))	Product of Tariff rate and Monthly Consumption

The above table can be accessed by following registers with address ranges.

Note:

1. In the Modbus server demo application (Energy Meter Demo), 500 registers were added from starting address of 2100 to 2600 to confirm the maximum register test validity for read-holding registers.An Exception occurs (Invalid data address) when try to write to the holding register of the specified address (2100 to 2600)

2. In the Modbus server demo application (Energy Meter Demo), 2500 registers were added from starting address of 2100 to 4600 to confirm the maximum register test validity for read-coil registers.An Exception occurs (Invalid data address) when try to write to the coil register of the specified address (2100 to 4600)

3. In Modbus Server Demo, if you read or write any register value (e.g., the I2 Alarm Level value), it must be read or written in the whole register set (e.g., 42003–42004). (Don’t read or write separately.)

Modbus Register Types

Register Type	Address Range
Coil Registers	(03001 to 03004)
Discrete Registers	(14001 to 14003)
Input Registers	(31001 to 31017)
Holding Registers	(42001 to 42028)

Modbus Error Codes

Error Name	Error Code
Invalid Function Code	1
Invalid Data Address	2
Invalid Data Value	3

User Configuration of server in RTU

Modbus Server Configuration

Serial Configuration	Values
COM PORT (Windows) USB PORT(Linux)	COM1 , COM5 …(Windows) /dev/ttyUSB1 (Linux)
BAUDRATE	9600 , 115200, ….

User Configuration of server in TCP

Modbus Server Configuration (TCP)

socket Configuration	Values
IP (windows /Linux)	192.168.29.39 ,…
Port	10,502, ….