In particular, through banner grabbing, it is possible to obtain information about the vendor, product and/or version of the software that runs behind a port. Value of zero means that connection is disconnected after every MODBUS transaction.Banner grabbing is the process of obtaining information about the infrastructure, or technology, behind a service. The connection is kept open at least the time specified here. How many times we try to establish the connection. How long to wait to before trying to establish a new connection after the previous one has been disconnected. How long to delay we must have at minimum between two consecutive MODBUS transactions. Use RTU encoding instead of regular TCP encoding. Also known as station address or unit identifier. Tcp is representing a particular Modbus TCP server (slave). When optional parameters are not specified, they default to the values shown in the table below. Required parameters must be specified in the. things file yourself, since it affects how the parameter value is encoded in the text file. Note that parameter type is very critical when writing. things file, although you can find the same parameters in the UI. The configuration in this documentation explains the. Things can be configured using the UI, or using a. In the tables below the thing configuration parameters are grouped by thing type.
See general documentation about serial port configuration to configure the serial port correctly. Otherwise you might encounter errors preventing all communication. With serial Modbus slaves, configuration of the serial port in openHAB is important. Other than the things themselves, there is no binding configuration. Typically one defines either tcp or serial bridge, depending on the variant of Modbus slave.įor each Modbus read request, a poller is defined.įinally, one ore more data things are introduced to extract relevant numbers from the raw Modbus data.įor write-only communication, data things can be introduced directly as children of tcp or serial bridges. Is child of poller (read-only or read-write things) or tcp/ serial (write-only things). Analogously, is responsible of converting openHAB commands to Modbus write requests. Thing for converting polled data to meaningful numbers. One poller corresponds to single Modbus read request (FC01, FC02, FC03, or FC04). Thing taking care of polling the data from modbus slaves. This binding supports 4 different things types Thing
Modbus parser (opens new window): tool to parse Modbus requests and responses.(opens new window): tool to convert numbers between different binary presentations.Simplymodbus.ca (opens new window): good reference as well as excellent tutorial like explanation of the protocol.Wikipedia article (opens new window): good read on modbus basics and addressing.Reader of the documentation should understand the basics of Modbus protocol. The binding does support Modbus RTU over Modbus TCP, (also known as "Modbus over TCP/IP" or "Modbus over TCP" or "Modbus RTU/IP"), as well as normal "Modbus TCP".The binding does not act as Modbus slave (e.g.Please note the following caveats or limitations The binding can also write data to Modbus slaves using FC05 (Write single coil), FC06 (Write single holding register), FC15 (Write multiple coils) or FC16 (Write multiple holding registers).
This polled data is converted to data suitable for use in openHAB.įunctionality exists to interpret typical number formats (e.g. The binding polls (or reads) Modbus data using function codes (FC) FC01 (Read coils), FC02 (Read discrete inputs), FC03 (Read multiple holding registers) or FC04 (Read input registers).
Support For 32, 64 Bit Value Types In Writing.Writing To Different Address And Type Than Read.