147 lines
4.6 KiB
Markdown
147 lines
4.6 KiB
Markdown
## MyEMS Modbus TCP Service
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### Introduction
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This service is a component of MyEMS to acquire data from Modbus TCP devices.
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[](https://app.codacy.com/gh/myems/myems-modbus-tcp?utm_source=github.com&utm_medium=referral&utm_content=myems/myems-modbus-tcp&utm_campaign=Badge_Grade_Settings)
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[](https://scrutinizer-ci.com/g/myems/myems-modbus-tcp/?branch=master)
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[](https://codeclimate.com/github/myems/myems-modbus-tcp/maintainability)
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[](https://lgtm.com/projects/g/myems/myems-modbus-tcp/alerts/)
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### Prerequisites
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pyserial
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modbus-tk
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mysql.connector
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### Installation
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Download and install MySQL Connector:
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```
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$ cd ~/tools
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$ wget https://dev.mysql.com/get/Downloads/Connector-Python/mysql-connector-python-8.0.20.tar.gz
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$ tar xzf mysql-connector-python-8.0.20.tar.gz
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$ cd ~/tools/mysql-connector-python-8.0.20
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$ sudo python3 setup.py install
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```
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Download and install modbus-tk
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```
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$ cd ~/tools
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$ git clone https://github.com/pyserial/pyserial.git
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$ cd ~/tools/pyserial
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$ sudo python3 setup.py install
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$ git clone https://github.com/ljean/modbus-tk.git
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$ cd ~/tools/modbus-tk
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$ sudo python3 setup.py install
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```
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Install myems-modbus-tcp service
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```
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$ cd ~
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$ git clone https://github.com/MyEMS/myems.git
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$ cd myems
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$ sudo git checkout master (or the latest release tag)
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$ sudo cp -R ~/myems/myems-modbus-tcp /myems-modbus-tcp
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```
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Eidt the config
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```
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$ sudo nano /myems-modbus-tcp/config.py
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```
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Setup systemd service:
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```
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$ sudo cp /myems-modbus-tcp/myems-modbus-tcp.service /lib/systemd/system/
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$ sudo systemctl enable myems-modbus-tcp.service
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$ sudo systemctl start myems-modbus-tcp.service
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```
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### Add Data Sources and Points in MyEMS Admin
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NOTE: If you modified Modbus TCP datasources and points, please restart this service:
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```
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$ sudo systemctl restart myems-modbus-tcp.service
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```
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Input Data source protocol:
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```
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modbus-tcp
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```
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Data source connection example:
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```
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{"host":"10.9.67.99","port":502}
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```
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Point address example:
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```
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{"slave_id":1, "function_code":3, "offset":0, "number_of_registers":2, "format":"<f", "byte_swap":true}
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```
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### Address
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#### slave_id
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The slave ID
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#### function_code
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01 (0x01) Read Coils
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02 (0x02) Read Discrete Inputs
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03 (0x03) Read Holding Registers
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04 (0x04) Read Input Registers
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23 (0x17) Read/Write Multiple registers
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#### offset
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The starting register address specified in the Request PDU
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#### number_of_registers
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The number of registers specified in the Request PDU
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#### format
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Use python3 library struct to format bytes.
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Python bytes objects are used to hold the data representing the C struct
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and also as format strings (explained below) to describe the layout of data in the C struct.
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The optional first format char indicates byte order, size and alignment:
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@: native order, size & alignment (default)
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=: native order, std. size & alignment
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<: little-endian, std. size & alignment
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>: big-endian, std. size & alignment
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!: same as >
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The remaining chars indicate types of args and must match exactly;
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these can be preceded by a decimal repeat count:
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x: pad byte (no data); c:char; b:signed byte; B:unsigned byte;
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?: _Bool (requires C99; if not available, char is used instead)
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h:short; H:unsigned short; i:int; I:unsigned int;
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l:long; L:unsigned long; f:float; d:double.
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Special cases (preceding decimal count indicates length):
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s:string (array of char); p: pascal string (with count byte).
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Special cases (only available in native format):
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n:ssize_t; N:size_t;
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P:an integer type that is wide enough to hold a pointer.
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Special case (not in native mode unless 'long long' in platform C):
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q:long long; Q:unsigned long long
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Whitespace between formats is ignored.
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#### byte_swap
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A boolean indicates whether or not to swap adjacent bytes.
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Swap adjacent bytes of 32bits(4bytes) or 64bits(8bytes).
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This is not for little-endian and big-endian swapping, and use format for that.
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The option is effective when number_of_registers is ether 2(32bits) or 4(64bits),
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else it will be ignored.
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### References
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[1]. http://myems.io
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[2]. http://www.modbus.org/tech.php
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[3]. https://github.com/ljean/modbus-tk
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[4]. https://docs.python.org/3/library/struct.html#format-strings |