Update modbus.go

[meimz]

More slave_id repair the same serial port name problem

--- PASS: TestRetrySuccessful (0.00s)
=== RUN TestRetryFailExhausted
2021/10/13 17:24:46 D! [] trying to read coil@0[1]...
2021/10/13 17:24:46 I! [] Device busy! Retrying 2 more time(s)...
2021/10/13 17:24:46 D! [] trying to read coil@0[1]...
2021/10/13 17:24:46 I! [] Device busy! Retrying 1 more time(s)...
2021/10/13 17:24:46 D! [] trying to read coil@0[1]...
--- PASS: TestRetryFailExhausted (0.00s)
=== RUN TestRetryFailIllegal
2021/10/13 17:24:46 D! [] trying to read coil@0[1]...
--- PASS: TestRetryFailIllegal (0.00s)
PASS
ok github.com/influxdata/telegraf/plugins/inputs/modbus 0.647s

Required for all PRs:

• Updated associated README.md.
• Wrote appropriate unit tests.
• Pull request title or commits are in conventional commit format

resolves #

[telegraf-tiger]

Thanks so much for the pull request!
🤝 ✒️ Just a reminder that the CLA has not yet been signed, and we'll need it before merging. Please sign the CLA when you get a chance, then post a comment here saying !signed-cla

[meimz]

!signed-cla

[telegraf-tiger]

Thanks so much for the pull request!
🤝 ✒️ Just a reminder that the CLA has not yet been signed, and we'll need it before merging. Please sign the CLA when you get a chance, then post a comment here saying !signed-cla

[meimz]

Thanks so much for the pull request! 🤝 ✒️ Just a reminder that the CLA has not yet been signed, and we'll need it before merging. Please sign the CLA when you get a chance, then post a comment here saying !signed-cla

!signed-cla

[srebhan]

@meimz what are you trying to fix with this PR?

[meimz]

@meimz what are you trying to fix with this PR?

The same serial port name whith different slave_id

@meimz what are you trying to fix with this PR?

[srebhan]

There already is PR #9279 which adds this feature. Is this what you are looking for?

[meimz]

There already is PR #9279 which adds this feature. Is this what you are looking for?

Yes，That is right！But PR #9279 is not solve different configuration node use the same contorller .

`[[inputs.modbus]]
interval = "1s"
name = "Temperature Humidity"
slave_id = 2
timeout = "1s"
controller = "file:///dev/ttyU1"
baud_rate = 9600
data_bits = 8
parity = "N"
stop_bits = 1
transmission_mode = "RTU"
input_registers = [
{ name = "temperature", byte_order = "AB", data_type = "INT16", scale=1.0, address = [0]},
{ name = "humidity", byte_order = "AB", data_type = "INT16", scale=1.0, address = [1]},
]

[[inputs.modbus]]
interval = "1s"
name = "Temperature Humidity"
slave_id = 1
timeout = "1s"
controller = "file:///dev/ttyU1"
baud_rate = 9600
data_bits = 8
parity = "N"
stop_bits = 1
transmission_mode = "RTU"
input_registers = [
{ name = "temperature", byte_order = "AB", data_type = "INT16", scale=1.0, address = [0]},
{ name = "humidity", byte_order = "AB", data_type = "INT16", scale=1.0, address = [1]},
]
`

[meimz]

1. I want one device one configuration node.
2. RS485 modbus devices can in series .

`[[inputs.modbus]]
interval = "1s"
name = "Temperature Humidity"
slave_id = 2
timeout = "1s"
controller = "file:///dev/ttyU1"
baud_rate = 9600
data_bits = 8
parity = "N"
stop_bits = 1
transmission_mode = "RTU"
input_registers = [
{ name = "temperature", byte_order = "AB", data_type = "INT16", scale=1.0, address = [0]},
{ name = "humidity", byte_order = "AB", data_type = "INT16", scale=1.0, address = [1]},
]

[[inputs.modbus]]
interval = "1s"
name = "Temperature Humidity"
slave_id = 1
timeout = "1s"
controller = "file:///dev/ttyU1"
baud_rate = 9600
data_bits = 8
parity = "N"
stop_bits = 1
transmission_mode = "RTU"
input_registers = [
{ name = "temperature", byte_order = "AB", data_type = "INT16", scale=1.0, address = [0]},
{ name = "humidity", byte_order = "AB", data_type = "INT16", scale=1.0, address = [1]},
]`

3.Do not modify the configuration file above and this PR can run.

[srebhan]

@meimz I understand your point, but I think we should not support this. With your PR you add a state to the plugin which in turn adds complexity such as caches etc. Imaging one plugin now disconnects or sets different parameters for the same interface (e.g. different timeout, baud rate, transmission mode)... Right now (and I also think with #9279) the program flow is easy to follow and robust which will change with this PR.