README
¶
Modbus Input Plugin
The Modbus plugin collects Discrete Inputs, Coils, Input Registers and Holding Registers via Modbus TCP or Modbus RTU/ASCII.
Global configuration options
In addition to the plugin-specific configuration settings, plugins support additional global and plugin configuration settings. These settings are used to modify metrics, tags, and field or create aliases and configure ordering, etc. See the CONFIGURATION.md for more details.
Configuration
# Retrieve data from MODBUS slave devices
[[inputs.modbus]]
## Connection Configuration
##
## The plugin supports connections to PLCs via MODBUS/TCP, RTU over TCP, ASCII over TCP or
## via serial line communication in binary (RTU) or readable (ASCII) encoding
##
## Device name
name = "Device"
## Slave ID - addresses a MODBUS device on the bus
## Range: 0 - 255 [0 = broadcast; 248 - 255 = reserved]
slave_id = 1
## Timeout for each request
timeout = "1s"
## Maximum number of retries and the time to wait between retries
## when a slave-device is busy.
# busy_retries = 0
# busy_retries_wait = "100ms"
# TCP - connect via Modbus/TCP
controller = "tcp://localhost:502"
## Serial (RS485; RS232)
## For unix-like operating systems use:
# controller = "file:///dev/ttyUSB0"
## For Windows operating systems use:
# controller = "COM1"
# baud_rate = 9600
# data_bits = 8
# parity = "N"
# stop_bits = 1
## Transmission mode for Modbus packets depending on the controller type.
## For Modbus over TCP you can choose between "TCP" , "RTUoverTCP" and
## "ASCIIoverTCP".
## For Serial controllers you can choose between "RTU" and "ASCII".
## By default this is set to "auto" selecting "TCP" for ModbusTCP connections
## and "RTU" for serial connections.
# transmission_mode = "auto"
## Trace the connection to the modbus device as debug messages
## Note: You have to enable telegraf's debug mode to see those messages!
# debug_connection = false
## Define the configuration schema
## |---register -- define fields per register type in the original style (only supports one slave ID)
## |---request -- define fields on a requests base
configuration_type = "register"
## --- "register" configuration style ---
## Measurements
##
## Digital Variables, Discrete Inputs and Coils
## measurement - the (optional) measurement name, defaults to "modbus"
## name - the variable name
## address - variable address
discrete_inputs = [
{ name = "start", address = [0]},
{ name = "stop", address = [1]},
{ name = "reset", address = [2]},
{ name = "emergency_stop", address = [3]},
]
coils = [
{ name = "motor1_run", address = [0]},
{ name = "motor1_jog", address = [1]},
{ name = "motor1_stop", address = [2]},
]
## Analog Variables, Input Registers and Holding Registers
## measurement - the (optional) measurement name, defaults to "modbus"
## name - the variable name
## byte_order - the ordering of bytes
## |---AB, ABCD - Big Endian
## |---BA, DCBA - Little Endian
## |---BADC - Mid-Big Endian
## |---CDAB - Mid-Little Endian
## data_type - INT8L, INT8H, UINT8L, UINT8H (low and high byte variants)
## INT16, UINT16, INT32, UINT32, INT64, UINT64,
## FLOAT16-IEEE, FLOAT32-IEEE, FLOAT64-IEEE (IEEE 754 binary representation)
## FLOAT32, FIXED, UFIXED (fixed-point representation on input)
## scale - the final numeric variable representation
## address - variable address
holding_registers = [
{ name = "power_factor", byte_order = "AB", data_type = "FIXED", scale=0.01, address = [8]},
{ name = "voltage", byte_order = "AB", data_type = "FIXED", scale=0.1, address = [0]},
{ name = "energy", byte_order = "ABCD", data_type = "FIXED", scale=0.001, address = [5,6]},
{ name = "current", byte_order = "ABCD", data_type = "FIXED", scale=0.001, address = [1,2]},
{ name = "frequency", byte_order = "AB", data_type = "UFIXED", scale=0.1, address = [7]},
{ name = "power", byte_order = "ABCD", data_type = "UFIXED", scale=0.1, address = [3,4]},
]
input_registers = [
{ name = "tank_level", byte_order = "AB", data_type = "INT16", scale=1.0, address = [0]},
{ name = "tank_ph", byte_order = "AB", data_type = "INT16", scale=1.0, address = [1]},
{ name = "pump1_speed", byte_order = "ABCD", data_type = "INT32", scale=1.0, address = [3,4]},
]
## --- "request" configuration style ---
## Per request definition
##
## Define a request sent to the device
## Multiple of those requests can be defined. Data will be collated into metrics at the end of data collection.
[[inputs.modbus.request]]
## ID of the modbus slave device to query.
## If you need to query multiple slave-devices, create several "request" definitions.
slave_id = 1
## Byte order of the data.
## |---ABCD -- Big Endian (Motorola)
## |---DCBA -- Little Endian (Intel)
## |---BADC -- Big Endian with byte swap
## |---CDAB -- Little Endian with byte swap
byte_order = "ABCD"
## Type of the register for the request
## Can be "coil", "discrete", "holding" or "input"
register = "coil"
## Name of the measurement.
## Can be overriden by the individual field definitions. Defaults to "modbus"
# measurement = "modbus"
## Request optimization algorithm.
## |---none -- Do not perform any optimization and use the given layout(default)
## |---shrink -- Shrink requests to actually requested fields
## | by stripping leading and trailing omits
## |---rearrange -- Rearrange request boundaries within consecutive address ranges
## | to reduce the number of requested registers by keeping
## | the number of requests.
## |---aggressive -- Rearrange request boundaries similar to "rearrange" but
## | allow to request registers not specified by the user to
## | fill gaps. This usually reduces the number of requests at the
## | cost of more requested registers.
## |---max_insert -- Rearrange request keeping the number of extra fields below the value
## provided in "optimization_max_register_fill". It is not necessary to define 'omitted'
## fields as the optimisation will add such field only where needed.
# optimization = "none"
## Maximum number register the optimizer is allowed to insert between two fields to
## save requests.
## This option is only used for the 'max_insert' optimization strategy.
## NOTE: All omitted fields are ignored, so this option denotes the effective hole
## size to fill.
# optimization_max_register_fill = 50
## Field definitions
## Analog Variables, Input Registers and Holding Registers
## address - address of the register to query. For coil and discrete inputs this is the bit address.
## name *1 - field name
## type *1,2 - type of the modbus field, can be
## INT8L, INT8H, UINT8L, UINT8H (low and high byte variants)
## INT16, UINT16, INT32, UINT32, INT64, UINT64 and
## FLOAT16, FLOAT32, FLOAT64 (IEEE 754 binary representation)
## scale *1,2 - (optional) factor to scale the variable with
## output *1,2 - (optional) type of resulting field, can be INT64, UINT64 or FLOAT64. Defaults to FLOAT64 if
## "scale" is provided and to the input "type" class otherwise (i.e. INT* -> INT64, etc).
## measurement *1 - (optional) measurement name, defaults to the setting of the request
## omit - (optional) omit this field. Useful to leave out single values when querying many registers
## with a single request. Defaults to "false".
##
## *1: Those fields are ignored if field is omitted ("omit"=true)
##
## *2: Thise fields are ignored for both "coil" and "discrete"-input type of registers. For those register types
## the fields are output as zero or one in UINT64 format by default.
## Coil / discrete input example
fields = [
{ address=0, name="motor1_run"},
{ address=1, name="jog", measurement="motor"},
{ address=2, name="motor1_stop", omit=true},
{ address=3, name="motor1_overheating"},
]
[inputs.modbus.request.tags]
machine = "impresser"
location = "main building"
[[inputs.modbus.request]]
## Holding example
## All of those examples will result in FLOAT64 field outputs
slave_id = 1
byte_order = "DCBA"
register = "holding"
fields = [
{ address=0, name="voltage", type="INT16", scale=0.1 },
{ address=1, name="current", type="INT32", scale=0.001 },
{ address=3, name="power", type="UINT32", omit=true },
{ address=5, name="energy", type="FLOAT32", scale=0.001, measurement="W" },
{ address=7, name="frequency", type="UINT32", scale=0.1 },
{ address=8, name="power_factor", type="INT64", scale=0.01 },
]
[inputs.modbus.request.tags]
machine = "impresser"
location = "main building"
[[inputs.modbus.request]]
## Input example with type conversions
slave_id = 1
byte_order = "ABCD"
register = "input"
fields = [
{ address=0, name="rpm", type="INT16" }, # will result in INT64 field
{ address=1, name="temperature", type="INT16", scale=0.1 }, # will result in FLOAT64 field
{ address=2, name="force", type="INT32", output="FLOAT64" }, # will result in FLOAT64 field
{ address=4, name="hours", type="UINT32" }, # will result in UIN64 field
]
[inputs.modbus.request.tags]
machine = "impresser"
location = "main building"
## Enable workarounds required by some devices to work correctly
# [inputs.modbus.workarounds]
## Pause after connect delays the first request by the specified time.
## This might be necessary for (slow) devices.
# pause_after_connect = "0ms"
## Pause between read requests sent to the device.
## This might be necessary for (slow) serial devices.
# pause_between_requests = "0ms"
## Close the connection after every gather cycle.
## Usually the plugin closes the connection after a certain idle-timeout,
## however, if you query a device with limited simultaneous connectivity
## (e.g. serial devices) from multiple instances you might want to only
## stay connected during gather and disconnect afterwards.
# close_connection_after_gather = false
## Force the plugin to read each field in a separate request.
## This might be necessary for devices not conforming to the spec,
## see https://github.com/influxdata/telegraf/issues/12071.
# one_request_per_field = false
Notes
You can debug Modbus connection issues by enabling debug_connection. To see
those debug messages, Telegraf has to be started with debugging enabled
(i.e. with the --debug option). Please be aware that connection tracing will
produce a lot of messages and should NOT be used in production environments.
Please use pause_after_connect / pause_between_requests with care. Ensure
the total gather time, including the pause(s), does not exceed the configured
collection interval. Note that pauses add up if multiple requests are sent!
Configuration styles
The modbus plugin supports multiple configuration styles that can be set using
the configuration_type setting. The different styles are described
below. Please note that styles cannot be mixed, i.e. only the settings belonging
to the configured configuration_type are used for constructing modbus
requests and creation of metrics.
Directly jump to the styles:
register configuration style
This is the original style used by this plugin. It allows a per-register configuration for a single slave-device.
Usage of data_type
The field data_type defines the representation of the data value on input from
the modbus registers. The input values are then converted from the given
data_type to a type that is appropriate when sending the value to the output
plugin. These output types are usually one of string, integer or
floating-point-number. The size of the output type is assumed to be large enough
for all supported input types. The mapping from the input type to the output
type is fixed and cannot be configured.
INT8L, INT8H, UINT8L, UINT8HThese types are used for 8-bit integer values. Select the one that matches your
modbus data source. The L and H suffix denotes the low- and high byte of
the register respectively.
INT16, UINT16, INT32, UINT32, INT64, UINT64These types are used for integer input values. Select the one that matches your modbus data source.
FLOAT16-IEEE, FLOAT32-IEEE, FLOAT64-IEEEUse these types if your modbus registers contain a value that is encoded in this format. These types always include the sign, therefore no variant exists.
FIXED, UFIXED (FLOAT32)These types are handled as an integer type on input, but are converted to floating point representation for further processing (e.g. scaling). Use one of these types when the input value is a decimal fixed point representation of a non-integer value.
Select the type UFIXED when the input type is declared to hold unsigned
integer values, which cannot be negative. The documentation of your modbus
device should indicate this by a term like 'uint16 containing fixed-point
representation with N decimal places'.
Select the type FIXED when the input type is declared to hold signed integer
values. Your documentation of the modbus device should indicate this with a term
like 'int32 containing fixed-point representation with N decimal places'.
(FLOAT32 is deprecated and should not be used. UFIXED provides the same conversion from unsigned values).
request configuration style
This style can be used to specify the modbus requests directly. It enables
specifying multiple [[inputs.modbus.request]] sections including multiple
slave-devices. This way, modbus gateway devices can be queried. Please note
that requests might be split for non-consecutive addresses. If you want to
avoid this behavior please add fields with the omit flag set filling the
gaps between addresses.
Slave device
You can use the slave_id setting to specify the ID of the slave device to
query. It should be specified for each request, otherwise it defaults to
zero. Please note, only one slave_id can be specified per request.
Byte order of the register
The byte_order setting specifies the byte and word-order of the registers. It
can be set to ABCD for big endian (Motorola) or DCBA for little endian
(Intel) format as well as BADC and CDAB for big endian or little endian
with byte swap.
Register type
The register setting specifies the modbus register-set to query and can be set
to coil, discrete, holding or input.
Per-request measurement setting
You can specify the name of the measurement for the following field definitions
using the measurement setting. If the setting is omitted modbus is
used. Furthermore, the measurement value can be overridden by each field
individually.
Optimization setting
Please only use request optimization if you do understand the implications!
The optimization setting can be used to optimize the actual requests sent to
the device. The following algorithms are available
none (default)Do not perform any optimization. Please note that the requests are still obeying
the maximum request sizes. Furthermore, completely empty requests, i.e. all
fields specify omit=true, are removed. Otherwise, the requests are sent as
specified by the user including request of omitted fields. This setting should
be used if you want full control over the requests e.g. to accommodate for
device constraints.
shrinkThis optimization allows to remove leading and trailing fields from requests if those fields are omitted. This can shrink the request number and sizes in cases where you specify large amounts of omitted fields, e.g. for documentation purposes.
rearrangeRequests are processed similar to shrink but the request boundaries are
rearranged such that usually less registers are being read while keeping the
number of requests. This optimization algorithm only works on consecutive
address ranges and respects user-defined gaps in the field addresses.
Please note: This optimization might take long in case of many non-consecutive, non-omitted fields!
aggressiveRequests are processed similar to rearrange but user-defined gaps in the field
addresses are filled automatically. This usually reduces the number of requests,
but will increase the number of registers read due to larger requests.
This algorithm might be useful if you only want to specify the fields you are
interested in but want to minimize the number of requests sent to the device.
Please note: This optimization might take long in case of many non-consecutive, non-omitted fields!
max_insertFields are assigned to the same request as long as the hole between the fields
do not exceed the maximum fill size given in optimization_max_register_fill.
User-defined omitted fields are ignored and interpreted as holes, so the best
practice is to not manually insert omitted fields for this optimizer. This
allows to specify only actually used fields and let the optimizer figure out
the request organization which can dramatically improve query time. The
trade-off here is between the cost of reading additional registers trashed
later and the cost of many requests.
Please note: The optimal value for optimization_max_register_fill depends
on the network and the queried device. It is hence recommended to test several
values and assess performance in order to find the best value. Use the
--test --debug flags to monitor how may requests are sent and the number of
touched registers.
Field definitions
Each request can contain a list of fields to collect from the modbus device.
A field is identified by an address that reflects the modbus register
address. You can usually find the address values for the different data-points
in the datasheet of your modbus device. This is a mandatory setting.
For coil and discrete input registers this setting specifies the bit containing the value of the field.
Using the name setting you can specify the field-name in the metric as output
by the plugin. This setting is ignored if the field's omit is set to true
and can be omitted in this case.
Please note: There cannot be multiple fields with the same name in one
metric identified by measurement, slave_id and register.
The type setting specifies the datatype of the modbus register and can be
set to INT8L, INT8H, UINT8L, UINT8H where L is the lower byte of the
register and H is the higher byte.
Furthermore, the types INT16, UINT16, INT32, UINT32, INT64 or UINT64
for integer types or FLOAT16, FLOAT32 and FLOAT64 for IEEE 754 binary
representations of floating point values exist. FLOAT16 denotes a
half-precision float with a 16-bit representation.
Usually the datatype of the register is listed in the datasheet of your modbus
device in relation to the address described above.
This setting is ignored if the field's omit is set to true or if the
register type is a bit-type (coil or discrete) and can be omitted in
these cases.
You can use the scale setting to scale the register values, e.g. if the
register contains a fix-point values in UINT32 format with two decimal places
for example. To convert the read register value to the actual value you can set
the scale=0.01. The scale is used as a factor e.g. field_value * scale.
This setting is ignored if the field's omit is set to true or if the
register type is a bit-type (coil or discrete) and can be omitted in these
cases.
Please note: The resulting field-type will be set to FLOAT64 if no output
format is specified.
Using the output setting you can explicitly specify the output
field-datatype. The output type can be INT64, UINT64 or FLOAT64. If not
set explicitly, the output type is guessed as follows: If scale is set to a
non-zero value, the output type is FLOAT64. Otherwise, the output type
corresponds to the register datatype class, i.e. INT* will result in
INT64, UINT* in UINT64 and FLOAT* in FLOAT64.
This setting is ignored if the field's omit is set to true or if the
register type is a bit-type (coil or discrete) and can be omitted in these
cases. For coil and discrete registers the field-value is output as zero or
one in UINT16 format.
per-field measurement setting
The measurement setting can be used to override the measurement name on a
per-field basis. This might be useful if you want to split the fields in one
request to multiple measurements. If not specified, the value specified in the
request section or, if also omitted,
modbus is used.
This setting is ignored if the field's omit is set to true and can be
omitted in this case.
omitting a field
When specifying omit=true, the corresponding field will be ignored when
collecting the metric but is taken into account when constructing the modbus
requests. This way, you can fill "holes" in the addresses to construct
consecutive address ranges resulting in a single request. Using a single modbus
request can be beneficial as the values are all collected at the same point in
time.
Tags definitions
Each request can be accompanied by tags valid for this request.
Please note: These tags take precedence over predefined tags such as name,
type or slave_id.
Metrics
Metrics are custom and configured using the discrete_inputs, coils,
holding_register and input_registers options.
Troubleshooting
Strange data
Modbus documentation is often a mess. People confuse memory-address (starts at one) and register address (starts at zero) or are unsure about the word-order used. Furthermore, there are some non-standard implementations that also swap the bytes within the register word (16-bit).
If you get an error or don't get the expected values from your device, you can try the following steps (assuming a 32-bit value).
If you are using a serial device and get a permission denied error, check the
permissions of your serial device and change them accordingly.
In case you get an exception '2' (illegal data address) error you might try to
offset your address entries by minus one as it is very likely that there is
confusion between memory and register addresses.
If you see strange values, the byte_order might be wrong. You can either probe
all combinations (ABCD, CDBA, BADC or DCBA) or set byte_order="ABCD" data_type="UINT32" and use the resulting value(s) in an online converter like
this. This especially makes sense if you don't want to mess
with the device, deal with 64-bit values and/or don't know the data_type of
your register (e.g. fix-point floating values vs. IEEE floating point).
If your data still looks corrupted, please post your configuration, error
message and/or the output of byte_order="ABCD" data_type="UINT32" to one of
the telegraf support channels (forum, slack or as an issue). If nothing helps,
please post your configuration, error message and/or the output of
byte_order="ABCD" data_type="UINT32" to one of the telegraf support channels
(forum, slack or as an issue).
Workarounds
Some Modbus devices need special read characteristics when reading data and will fail otherwise. For example, some serial devices need a pause between register read requests. Others might only support a limited number of simultaneously connected devices, like serial devices or some ModbusTCP devices. In case you need to access those devices in parallel you might want to disconnect immediately after the plugin finishes reading.
To enable this plugin to also handle those "special" devices, there is the
workarounds configuration option. In case your documentation states certain
read requirements or you get read timeouts or other read errors, you might want
to try one or more workaround options. If you find that other/more workarounds
are required for your device, please let us know.
In case your device needs a workaround that is not yet implemented, please open an issue or submit a pull-request.
Example Output
$ ./telegraf -config telegraf.conf -input-filter modbus -test
modbus.InputRegisters,host=orangepizero Current=0,Energy=0,Frequency=60,Power=0,PowerFactor=0,Voltage=123.9000015258789 1554079521000000000
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Configuration ¶ added in v1.19.0
type ConfigurationOriginal ¶ added in v1.19.0
type ConfigurationOriginal struct {
SlaveID byte `toml:"slave_id"`
DiscreteInputs []fieldDefinition `toml:"discrete_inputs"`
Coils []fieldDefinition `toml:"coils"`
HoldingRegisters []fieldDefinition `toml:"holding_registers"`
InputRegisters []fieldDefinition `toml:"input_registers"`
// contains filtered or unexported fields
}
func (*ConfigurationOriginal) Check ¶ added in v1.19.0
func (c *ConfigurationOriginal) Check() error
func (*ConfigurationOriginal) Process ¶ added in v1.19.0
func (c *ConfigurationOriginal) Process() (map[byte]requestSet, error)
func (*ConfigurationOriginal) SampleConfigPart ¶ added in v1.22.0
func (c *ConfigurationOriginal) SampleConfigPart() string
type ConfigurationPerRequest ¶ added in v1.22.0
type ConfigurationPerRequest struct {
Requests []requestDefinition `toml:"request"`
// contains filtered or unexported fields
}
func (*ConfigurationPerRequest) Check ¶ added in v1.22.0
func (c *ConfigurationPerRequest) Check() error
func (*ConfigurationPerRequest) Process ¶ added in v1.22.0
func (c *ConfigurationPerRequest) Process() (map[byte]requestSet, error)
func (*ConfigurationPerRequest) SampleConfigPart ¶ added in v1.22.0
func (c *ConfigurationPerRequest) SampleConfigPart() string
type Modbus ¶
type Modbus struct {
Name string `toml:"name"`
Controller string `toml:"controller"`
TransmissionMode string `toml:"transmission_mode"`
BaudRate int `toml:"baud_rate"`
DataBits int `toml:"data_bits"`
Parity string `toml:"parity"`
StopBits int `toml:"stop_bits"`
Timeout config.Duration `toml:"timeout"`
Retries int `toml:"busy_retries"`
RetriesWaitTime config.Duration `toml:"busy_retries_wait"`
DebugConnection bool `toml:"debug_connection"`
Workarounds ModbusWorkarounds `toml:"workarounds"`
Log telegraf.Logger `toml:"-"`
// Register configuration
ConfigurationType string `toml:"configuration_type"`
ConfigurationOriginal
ConfigurationPerRequest
// contains filtered or unexported fields
}
Modbus holds all data relevant to the plugin
func (*Modbus) Gather ¶
func (m *Modbus) Gather(acc telegraf.Accumulator) error
Gather implements the telegraf plugin interface method for data accumulation
func (*Modbus) SampleConfig ¶
SampleConfig returns a basic configuration for the plugin
Source Files