[jira] [Commented] (PLC4X-300) Plc4x support for RTU/Serial communication for modbus protocol.

["Ben Hutcheson (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PLC4X-300?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17552432#comment-17552432 ] 

Ben Hutcheson commented on PLC4X-300:
-------------------------------------

[~psham81] it would be great if you could provide some feedback on the new Modbus RTU driver that [~cdutz] has put together.

> Plc4x support for RTU/Serial communication for modbus protocol.
> ---------------------------------------------------------------
>
>                 Key: PLC4X-300
>                 URL: https://issues.apache.org/jira/browse/PLC4X-300
>             Project: Apache PLC4X
>          Issue Type: Bug
>          Components: Driver-Modbus, examples
>    Affects Versions: 0.8.0
>            Reporter: Purushotham YB
>            Priority: Major
>
> Hi,
>    I am using plc4x for one of our projects to develop a module which uses plc4x to establish communication with a sensor device using modbus RTU/Serial communication.
> I am able to communicate with the device with TCP transport but not able to do with RTU/Serial communication.
> I tried to look for some example/documentation on how to use RTU/Serial communication in plc4x but could not find any information in the website or the web.
> Also looking at the documentation at [https://plc4x.apache.org/users/protocols/modbus.html] it is not clear whether modbus supports serial transport as it only lists tcp and udp.
>  
> |Compatible Transports:| * {{tcp}} (Default Port: 502)
>  * {{udp}} (Default Port: 502)|
> Kindly request to clarify if serial is supported in modbus? if so could you please point me to an example/documentation which shall be used to understand how to use it for serial communication.
> Anyways I tried to use the library/driver plc4j-transport-serial  [https://plc4x.apache.org/users/transports/serial.html]
> to communicate with device in which the connection is established but it fails to read the data with following WANING.
>  
> {{2021-06-03-18:13:51.814 [nioEventLoopGroup-2-1] WARN  io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector org.apache.plc4x.java.transport.serial.SerialPollingSelector@28ecdc0d.}}
> {{2021-06-03-18:13:59.630 [nioEventLoopGroup-2-1] WARN  io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector org.apache.plc4x.java.transport.serial.SerialPollingSelector@11c9a1fa.}}
> {{My Sample code is as follows.}}
>  
> {{ private void plcRtuReader() {}}
> {{ // unit-identifier=1&}}
> {{ String connectionString =}}
> {{ "modbus:serial://COM5?unit-identifier=1&baudRate=19200&stopBits=" + SerialPort.ONE_STOP_BIT}}
> {{ + "&parityBits="}}
> {{ + SerialPort.NO_PARITY + "&dataBits=8";}}
> {{ System.out.println("URL:" + connectionString);}}
> {{ try (PlcConnection plcConnection = new PlcDriverManager().getConnection(connectionString)) {}}
> {{ if (!plcConnection.getMetadata().canRead()) {}}
> {{ System.out.println("This connection doesn't support reading.");}}
> {{ return;}}
> {{ }}}
> {{ PlcReadRequest.Builder builder = plcConnection.readRequestBuilder();}}
> {{ builder.addItem("value-2", "input-register:1[2]");}}
> {{PlcReadRequest readRequest = builder.build();}}
> {{// CompletableFuture<? extends PlcReadResponse> asyncResponse = readRequest.execute();}}
> {{ PlcReadResponse response = readRequest.execute().get();}}
> {{ for (String fieldName : response.getFieldNames()) {}}
> {{ if (response.getResponseCode(fieldName) == PlcResponseCode.OK) {}}
> {{ int numValues = response.getNumberOfValues(fieldName);}}
> {{ // If it's just one element, output just one single line.}}
> {{ if (numValues == 1) {}}
> {{ System.out.println("Value[" + fieldName + "]: " + response.getObject(fieldName));}}
> {{ }}}
> {{ // If it's more than one element, output each in a single row.}}
> {{ else {}}
> {{ System.out.println("Value[" + fieldName + "]:");}}
> {{ for (int i = 0; i < numValues; i++) {}}
> {{ System.out.println(" - " + response.getObject(fieldName, i));}}
> {{ }}}
> {{ }}}
> {{ }}}
> {{ // Something went wrong, to output an error message instead.}}
> {{ else {}}
> {{ System.out.println(}}
> {{ "Error[" + fieldName + "]: " + response.getResponseCode(fieldName).name());}}
> {{ }}}
> {{ }}}
> {{ System.exit(0);}}
> {{ } catch (PlcConnectionException e) {}}
> {{ e.printStackTrace();}}
> {{ } catch (Exception e) {}}
> {{ e.printStackTrace();}}
> {{ }}}
> {{ }}}
> Thanks a lot for your help.
> Regards,
> Purushotham



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