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Template:Networking rutos manual modbus (view source)
Revision as of 13:32, 1 September 2020
, 13:32, 1 September 2020→MQTT Gateway
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===Request messages===
----
Modbus request data sent in the MQTT payload should be generated in accordance with the following format:
<b>0 <COOKIE> <IP_TYPE> <IP> <PORT> <TIMEOUT> <SLAVE_ID> <MODBUS_FUNCTION> <REGISTER_NUMBER> <REGISTER_COUNT/VALUE></b>
Explanation:
<ul>
<li><b>0</b> - must be 0, which signifies a textual format (currently the only one implemented).</li>
<li><b>Cookie</b> - a 64-bit unsigned integer in range [0..2<sup>64</sup>]). A cookie is used in order to distinguish which response belongs to which request, each request and the corresponding response contain a matching cookie: a 64-bit unsigned integer.</li>
<li><b>IP type</b> - host IP address type. Possible values:
<ul>
<li><b>0</b> - IPv4 address;</li>
<li><b>1</b> - IPv6 address;</li>
<li><b>2</b> - hostname that will be resolved to an IP address.</li>
</ul></li>
<li><b>IP</b> - IP address of a Modbus TCP slave. IPv6 must be presented in full form (e.g., <i>2001:0db8:0000:0000:0000:8a2e:0370:7334</i>).</li>
<li><b>Port</b> - port number of the Modbus TCP slave.</li>
<li><b>Timeout</b> - timeoutfor Modbus TCP connection, in seconds. Range [1..999].</li>
<li><b>Slave ID</b> - Modbus TCP slave ID. Range [1..255].</li>
<li><b>Modbus function</b> - Only these are supported at the moment:
<ul>
<li><b>3</b> - read holding registers;</li>
<li><b>6</b> - write to a single holding register;</li>
<li><b>16</b> - write to multiple holding registers.</li>
</ul></li>
<li><b>Register number</b> - number of the first register (in range [1..65536]) from which the registers will be read/written to.
<li><b>Register count/value</b> - this value depends on the Modbus function:
<ul>
<li>if modbus function is <b>3</b> - <u>register count</u> (in range [1..125]); must not exceed the boundary (first register number + register count <= 65537);</li>
<li>if modbus function is <b>6</b> - <u>register value</u> (in range [0..65535]);</li>
<li>if modbus function is <b>16</b> - <u>register count</u> (in range [1..123]); must not exceed the boundary (first register number + register count <= 65537); and <u>register values</u> separated with commas, without spaces (e.g., <i>1,2,3,654,21,789</i>); there must be exactly as many values as specified (with register count); each value must be in the range of [0..65535].</li>
</ul></li>
</ul>
===Response messages===
----
A special response message can take one of the following forms:
<COOKIE> OK - <i>for functions 6 and 16</i>
<COOKIE> OK <VALUE> <VALUE> <VALUE>... - <i>for function 3, where <VALUE> <VALUE> <VALUE>... are read register values</i>
<COOKIE> ERROR: ... - <i>for failures, where ... is the error description</i>
===Examples===
----
Below are a few <b>examples</b> of controlling/monitoring the internal Modbus TCP Slave on {{{name}}}.
----
<b>Reboot the device</b>
<ul>
<li>Request:<br><pre>0 65432 0 192.168.1.1 502 5 1 6 206 1</pre></li>
<li>Response:<br><pre>65432 OK</pre></li>
</ul>
----
<b>Retrieve uptime</b>
<ul>
<li>Request:<br><pre>0 65432 0 192.168.1.1 502 5 1 3 2 2</pre></li>
<li>Response:<br><pre>65432 OK 0 5590</pre></li>
</ul>
----
If you're using Eclipse Mosquitto (MQTT implementation used on {{{name}}}), Publish/Subscribe commands may look something like this:
<b>Retrieve uptime</b>
<ul>
<li>Request:<br><pre>mosquitto_pub -h 192.168.1.1 -p 1883 -t request -m "0 65432 0 192.168.1.1 502 5 1 3 2 2"</pre></li>
<li>Response:<br><pre>mosquitto_sub -h 192.168.1.1 -p 1883 -t response
65432 OK 0 5590</pre></li>
</ul>
==See also==
==See also==
