skyformat99 / modbusd

Modbus master daemon based on libmodbus

modbusd

Modbus master daemon

• Support doxygen style comments.
• ZMQ is a high-level message library, you can plug in your own socket implemetations without losing the core functionalities.

TOC

• Design
• Setup
• Continuous Integration
• Documentation

---

Design

Implemented libmodbus function codes

FC	Description	API
0x01	read coils	int modbus_read_bits(modbus_t *ctx, int addr, int nb, uint8_t *dest)
0x02	read discrete input	int modbus_read_input_bits(modbus_t *ctx, int addr, int nb, uint8_t *dest)
0x03	read holding registers	int modbus_read_registers(modbus_t *ctx, int addr, int nb, uint16_t *dest)
0x04	read input registers	int modbus_read_input_registers(modbus_t *ctx, int addr, int nb, uint16_t *dest)
0x05	write single coil	int modbus_write_bit(modbus_t *ctx, int addr, int status)
0x06	write single register	int modbus_write_register(modbus_t *ctx, int addr, int value)
0x0F	write multi coils	int modbus_write_bits(modbus_t *ctx, int addr, int nb, const uint8_t *src)
0x10	write multi registers	int modbus_write_registers(modbus_t *ctx, int addr, int nb, const uint16_t *src)

coil/register number and address table

Coil/Register numbers	data address	type	table name	offset	function code
1-9999	0000 to 270E (9998)	Read-Write	Discrete Output Coils	1	1, 5, 15
10001-19999	0000 to 270E (9998)	Read-Only	Discrete Input Contacts	10001	2
30001-39999	0000 to 270E (9998)	Read-Only	Analog Input Registers	30001	4
40001-49999	0000 to 270E (9998)	Read-Write	Analog Output Holding Registers	40001	3, 6, 16

---

Configuration file format

{
    "syslog": 1,
    "ipc_sub": "ipc:///tmp/to.modbus",
    "ipc_pub": "ipc:///tmp/from.modbus",
    "mbtcp_connect_timeout": 200000
}

Modbus TCP Json command format

-> mbtcp read request

{
	"ip": "192.168.3.2",
	"port": "502",
	"slave": 22,
	"tid": 1,
	"cmd": "fc1",
	"addr": 250,
	"len": 10
}

<- mbtcp read reponse

{
	"tid": 1,
	"data": [1,2,3,4],
	"status": "ok"
}

-> mbtcp write request

{
	"ip": "192.168.3.2",
	"port": "502",
	"slave": 22,
	"tid": 1,
	"cmd": "fc5",
	"addr": 80,
	"len": 4,
	"data": [1,2,3,4]
}

<- mbtcp write response

{
	"tid": 1,
	"status": "ok"
}

-> mbtcp set timeout

{
	"tid": 1,
	"cmd": "timeout",
	"data": 210000
}

<- mbtcp set timeout response

{
	"tid": 1,
	"status": "ok"
}

External libraries

• libmodbus
• libzmq
• czmq
• uthash
• cJSON

---

Library documentations

• uthash user guide
• libmodbus api document
• libmodbus header
• cJSON examples

Flow Chart

---

Setup

Step by step from scratch or (Travis CI + Docker)

Setup development dependencies

sudo apt-get update
sudo apt-get install -y git build-essential autoconf libtool pkg-config cmake

---

Setup OSS libs dependencies

Install libmodbus library (3.1.4)

git clone https://github.com/stephane/libmodbus/
cd libmodbus
./autogen.sh
./configure
make
sudo make install
sudo ldconfig

Install libzmq (3.2.5)

wget https://github.com/zeromq/zeromq3-x/releases/download/v3.2.5/zeromq-3.2.5.tar.gz
tar xvzf zeromq-3.2.5.tar.gz
cd zeromq-3.2.5
./configure
make
sudo make install
sudo ldconfig

Install czmq (high-level C binding for zeromq)

git clone git://github.com/zeromq/czmq.git
cd czmq
./autogen.sh
./configure
make
sudo make install
sudo ldconfig

Setup testing environment

Install node.js 4.x & zmq binding on ubuntu

curl -sL https://deb.nodesource.com/setup_4.x | sudo -E bash -
sudo apt-get install -y nodejs
sudo npm install -g zmq

---

Build

git clone modbusd
cd modbusd
mkdir build
cd build
cmake ..
make
./modbusd ../modbusd.json # load external configuration file

---

Continuous Integration

We do continuous integration and update docker images after git push by Travis CI.

// x86_64 platform

Docker base images

• x86_64 git repo
• docker hub

Docker images registry

You can download pre-built docker images according to the following commands.

• docker pull takawang/modbus-server
• docker pull takawang/modbus-zclient
• docker pull takawang/modbusd

Docker images and testing from the scratch

# build simulation server image
docker build -t takawang/modbus-server tests/mbserver/.
# build zclient image
docker build -t takawang/modbus-zclient tests/zclient/.
# build modbusd image
docker build -t takawang/modbusd .

# run modbus server
docker run -itd --name=slave takawang/modbus-server
# run modbusd
docker run -v /tmp:/tmp --link slave -it --name=modbusd takawang/modbusd
# run zclient
docker run -v /tmp:/tmp -it --link slave takawang/modbus-zclient

Docker composer

# build & run
docker-compose up 
# exit test
ctrl+c

// armhf

Docker base images

• armhf git repo
• docker hub

Docker images registry

You can download pre-built docker images according to the following commands.

• docker pull takawang/arm-modbus-server
• docker pull takawang/arm-modbus-zclient
• docker pull takawang/arm-modbusd

Docker images and testing from the scratch

# build simulation server image
docker build -t takawang/arm-modbus-server -f tests/mbserver/Dockerfile.arm .
# build zclient image
docker build -t takawang/arm-modbus-zclient tests/zclient/Dockerfile.arm .
# build modbusd image
docker build -t takawang/arm-modbusd -f Dockerfile.arm .

# run modbus server
docker run -itd --name=slave takawang/arm-modbus-server
# run modbusd
docker run -v /tmp:/tmp --link slave -it --name=modbusd takawang/arm-modbusd
# run zclient
docker run -v /tmp:/tmp -it --link slave takawang/arm-modbus-zclient

Deployment Diagram

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Documentations

• API Document