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https://issues.apache.org/jira/browse/PLC4X-300?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17357263#comment-17357263
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Juan García commented on PLC4X-300:
-----------------------------------
Hello [~cdutz]!
Thank you very much for the information, we are working in developing a custom
Azure IoT module to connect the edge with our iiot platform (Purush is in our
team). For us is important to have both choices (TCP and RTU options).
Is nice to hear that you are working on improving the SDK. If you need support
from our side please do not hesitate to contact me.
Juan
> 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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