[ https://issues.apache.org/jira/browse/PLC4X-341 ]
Andy Grebe deleted comment on PLC4X-341:
----------------------------------
was (Author: JIRAUSER289106):
Hi Chris,
I started to build(well, attempted) plc4x on a windows machine. I have maven and jdk 18, but I'm getting the following errors and can't find a solution googling.
[ERROR] /C:/Users/agrebe/Documents/GitHub/plc4x/code-generation/protocol-base-mspec/src/main/java/org/apache/plc4x/plugins/codegenerator/language/mspec/expression/ExpressionStringListener.java:[41,55] cannot find symbol
[ERROR] symbol: class ExpressionStringContext
[ERROR] location: class com.sun.tools.example.debug.expr.ExpressionParser
[ERROR] /C:/Users/agrebe/Documents/GitHub/plc4x/code-generation/protocol-base-mspec/src/main/java/org/apache/plc4x/plugins/codegenerator/language/mspec/expression/ExpressionStringListener.java:[47,54] cannot find symbol
[ERROR] symbol: class ExpressionStringContext
[ERROR] location: class com.sun.tools.example.debug.expr.ExpressionParser
> PLC4J GIP/CIP Read STRING tag returns null w/error
> --------------------------------------------------
>
> Key: PLC4X-341
> URL: https://issues.apache.org/jira/browse/PLC4X-341
> Project: Apache PLC4X
> Issue Type: Bug
> Components: Driver-Ethernet/IP, PLC4J
> Affects Versions: 0.9.1
> Reporter: Andy Grebe
> Priority: Major
> Attachments: eipcipstringread.pcapng
>
>
> STRING tag reads in plc4j using eip are not returning the string. The error returned is:
> java.lang.NullPointerException: Cannot invoke "org.apache.plc4x.java.api.value.PlcValue.getString()" because the return value of "org.apache.plc4x.java.api.messages.PlcReadResponse.getPlcValue(String)" is null
> It looks like plc4j is considering it a structure or array. If I read with
> {code:java}
> %MyString[{index}]:STRING:1 {code}
> I can get the individual characters in the string by placing the actual index in \{index}. So it knows where to start reading the data from.
> When running a wireshark cap, I can see the returned string in the response from the PLC. Attached is a pcap of the transaction.
>
> Code Snippet:
> {code:java}
> try (PlcConnection plcConnection = new PlcDriverManager().getConnection("eip://127.0.0.1")) {
> if (!plcConnection.getMetadata().canRead()) {
> logger.error("PLC connection doesn't support reading.");
> return;
> }
> logger.info("PLC connector connected"); // Create a new read request:
> PlcReadRequest.Builder builder = plcConnection.readRequestBuilder();
> logger.info("Created Builder");
> builder.addItem("value-1", "%MyString:STRING:1");
> PlcReadRequest readRequest = builder.build(); // Register a callback executed as soon as a response arrives.
> logger.info("Make sync request for PLC data");
> PlcReadResponse readResponse = readRequest.execute().get(5000, TimeUnit.MILLISECONDS);
> if (readResponse != null) {
> printPlcResponse(readResponse);
> } else {
> logger.error("An error reading PLC, response is NULL");
> }
> for (String field : readResponse.getFieldNames()){
> rtnArray.add(new PlcReadResponseData(field,
> readResponse.getPlcValue(field).getString()) ); // Exception is thrown here
> }
> } catch (PlcConnectionException e) {
> e.printStackTrace();
> } {code}
>
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