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59 lines
3.1 KiB
Markdown
59 lines
3.1 KiB
Markdown
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# Modbus TCP Master-Slave Example
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## Overview
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These two projects illustrate the communication between Modbus master and slave device in the segment.
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Master initializes Modbus interface driver and then reads parameters from slave device in the segment.
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After several successful read attempts slave sets the alarm relay (end of test condition).
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Once master reads the alarm it stops communication and destroy driver.
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The examples:
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* `examples/protocols/modbus/tcp/mb_tcp_master` - Modbus TCP master
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* `examples/protocols/modbus/tcp/mb_tcp_slave` - Modbus TCP slave
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See README.md for each individual project for more information.
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## How to use example
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### Hardware Required
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This example can be run on any commonly available ESP32(-S2) development board.
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The master and slave boards should be connected to the same network (see the README.md file in example folder) and slave address `CONFIG_MB_SLAVE_ADDR` be defined for slave board(s).
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See the connection schematic in README.md files of each example.
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### Configure the project
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This example test requires communication mode setting for master and slave be the same and slave address set to 1.
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Please refer to README.md files of each example project for more information. This example uses the default option `CONFIG_MB_SLAVE_IP_FROM_STDIN` to resolve slave IP address and supports IPv4 address type for communication in this case.
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## About common_component in this example
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The folder "mb_example_common" one level above includes definitions of parameter structures for master and slave device (both projects share the same parameters).
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However, currently it is for example purpose only and can be modified for particular application.
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## Example Output
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Refer to README.md file in the appropriate example folder for more information about master and slave log output.
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## Troubleshooting
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If the examples do not work as expected and slave and master boards are not able to communicate correctly it is possible to find the reason for errors.
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The most important errors are described in master example output and formatted as below:
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```
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E (1692332) MB_CONTROLLER_MASTER: mbc_master_get_parameter(111): SERIAL master get parameter failure error=(0x107) (ESP_ERR_TIMEOUT).
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```
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ESP_ERR_TIMEOUT (0x107) - Modbus slave device does not respond during configured timeout.
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Check ability for communication pinging each slave configured in the master parameter description table or use command on your host machine to find modbus slave using mDNS (requires `CONFIG_MB_MDNS_IP_RESOLVER` option be enabled):
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```>dns-sd -L mb_slave_tcp_XX _modbus._tcp .```
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where XX is the short slave address (index) of the slave configured in the Kconfig of slave example.
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Also it is possible to increase Kconfig value `CONFIG_FMB_MASTER_TIMEOUT_MS_RESPOND` to compensate network communication delays between master and slaves.
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ESP_ERR_NOT_SUPPORTED (0x106), ESP_ERR_INVALID_RESPONSE (0x108) - Modbus slave device does not support requested command or register and sent exeption response.
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ESP_ERR_INVALID_STATE (0x103) - Modbus stack is not configured correctly or can't work correctly due to critical failure.
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