The modbus_read node
Read data from a modbus slave device via modbus tcp, supported read functions are : ['coils', 'hregs', 'iregs', 'inputs', 'memory']
Reading can be done periodically (if every is given) and/or via a trigger (incoming value).
Read multiple values with possibly different functions at once.
The node will optimize reading by treating contiguous values as one reading var.
If the align property is set to true (default), the nodes's read times will be truncated to the every property
(For example, if the node is started at 12:06 and the every property is 5m then the next read will
occur at 12:10, then the next at 12:15 and so on, instead of 12:06, 12:11 and so on).
Examples
|modbus_read()
.ip('127.0.0.1')
.device(255)
.every(1s)
.function('coils', 'hregs', 'iregs', 'hregs')
.from(2127, 3008, 104, 30306)
.count(1, 2, 2, 4)
.as('data.EnergyConsumption', 'data.CurrentValue', 'data.EnergyDelivered')
.output('int16', 'float32', 'float32', 'double')
.signed(true, true, false, false)
|modbus_read()
.ip('127.0.0.1')
.every(2m)
.function('hregs', 'hregs', 'hregs')
.from(2127, 2125, 104)
.count(2, 2, 2)
.as('data.EnergyConsumption', 'data.CurrentValue', 'data.EnergyDelivered')
.output('float32', 'float32', 'float32')
Parameters
| Parameter | Description | Default |
|---|---|---|
ip( string ) |
ip address of modbus device | |
port( integer ) |
port of modbus device | 502 |
every( duration ) |
time between reads | undefined |
align( boolean ) |
align read intervals according to every | true |
device( integer ) |
modbus device id (0-255) | 255 |
function( string_list ) |
list of read functions, one of ['coils', 'hregs', 'iregs', 'inputs', 'memory'] |
|
from( integer_list ) |
list of start values | |
count( integer_list) |
list of count values, how much data to read for every function given | |
as( string_list ) |
output names for the read values | |
output( string_list ) |
list of output formats one of ['int16', 'int32', 'float32', 'double', 'coils', 'ascii', 'binary'] |
undefined |
signed( atom_list true/false) |
list of values indicating if values are signed | undefined |
round( integer ) |
Round all float32 and double values with the given precision. If a value has less than the given decimal places, it will be left untouched |
undefined (no rounding) |
timeout( duration ) |
Read timeout for one request | 5s |
Note that, if given, all read parameters(function, from, count, as, output, signed) must have the same length, this means if you have two
values you want to read :
.function('coils', 'hregs')`
all corresponding read params (if given) must have the same length:
.as('val1', 'val2')
.output(int16, float32)
.from(1,2)
.count(2,4)
.signed(true, true)