# \[Problem\] S71500 driver **URL:** \ **Category:** Ignition\ **Tags:** ignition80\ **Created:** [May 4, 2021, 12:00pm UTC](https://forum.inductiveautomation.com/t/problem-s71500-driver/46306 "2021-05-04T12:00:43Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![n.meluccio](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/n.meluccio/32/4858_2.png) [@n.meluccio](https://forum.inductiveautomation.com/u/n.meluccio)\ **Post date:** [May 4, 2021, 12:00pm UTC](https://forum.inductiveautomation.com/t/problem-s71500-driver/46306/1 "2021-05-04T12:00:43Z")
Hello there, i’m trying to write 20 PLC tags with a system.tag.writeBlocking. Sometimes (1 time on 3) the tags are not written to PLC and i get an error message on the Gateway logs page: **BasicRequestCycle** ```auto java.lang.NullPointerException: null at com.inductiveautomation.xopc.driver.util.UAByteUtilities.lambda$fromVariant$0(UAByteUtilities.java:205) at java.base/java.util.stream.ReferencePipeline$2$1.accept(Unknown Source) at java.base/java.util.Spliterators$ArraySpliterator.tryAdvance(Unknown Source) at java.base/java.util.stream.ReferencePipeline.forEachWithCancel(Unknown Source) at java.base/java.util.stream.AbstractPipeline.copyIntoWithCancel(Unknown Source) at java.base/java.util.stream.AbstractPipeline.copyInto(Unknown Source) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source) at java.base/java.util.stream.FindOps$FindOp.evaluateSequential(Unknown Source) at java.base/java.util.stream.AbstractPipeline.evaluate(Unknown Source) at java.base/java.util.stream.ReferencePipeline.findFirst(Unknown Source) at com.inductiveautomation.xopc.driver.util.UAByteUtilities.fromVariant(UAByteUtilities.java:206) at com.inductiveautomation.xopc.drivers.siemens.structs.converters.DefaultValueConverter.convertValue(DefaultValueConverter.java:41) at com.inductiveautomation.xopc.drivers.siemens.structs.writers.ValueBlockWriter.write(ValueBlockWriter.java:21) at com.inductiveautomation.xopc.drivers.siemens.structs.writers.S7WriteRequestDataWriter.write(S7WriteRequestDataWriter.java:20) at com.inductiveautomation.xopc.drivers.siemens.structs.writers.S7WriteRequestWriter.write(S7WriteRequestWriter.java:17) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest$1.write(WriteRequest.java:126) at com.inductiveautomation.xopc.drivers.siemens.protocols.TxPacket.(TxPacket.java:32) at com.inductiveautomation.xopc.drivers.siemens.protocols.ProtocolStack.transmit(ProtocolStack.java:23) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest.buildPacket(WriteRequest.java:123) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest.preparePacket(WriteRequest.java:112) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest.sendMessage(WriteRequest.java:105) at com.inductiveautomation.xopc.driver.api.requests.TimedRequest.sendMessage(TimedRequest.java:24) at com.inductiveautomation.xopc.driver.api.BasicRequestCycle$PendingRequest.sendMessage(BasicRequestCycle.java:420) at com.inductiveautomation.xopc.driver.api.BasicRequestCycle.sendRequest(BasicRequestCycle.java:233) at com.inductiveautomation.xopc.driver.api.BasicRequestCycle.run(BasicRequestCycle.java:145) at java.base/java.lang.Thread.run(Unknown Source) ``` i’m using S71500 direct driver, no third-party OPC involved. Ignition v8.1.4 stable Window 10 pro Thanks for you help. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [May 4, 2021, 12:41pm UTC](https://forum.inductiveautomation.com/t/problem-s71500-driver/46306/2 "2021-05-04T12:41:53Z")
This looks like it’s probably a bug in the driver. Open a ticket with support and provide as much details about what tags and values you’re writing when this happens as you can. ---
**Author:** ![j.abrante](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/j.abrante/32/10431_2.png) [@j.abrante](https://forum.inductiveautomation.com/u/j.abrante)\ **Post date:** [March 20, 2023, 9:40am UTC](https://forum.inductiveautomation.com/t/problem-s71500-driver/46306/3 "2023-03-20T09:40:18Z")
Some update about this problem? I have the same message ---
**Author:** ![Richard\_Marquez](https://avatars.discourse-cdn.com/v4/letter/r/13edae/32.png) [@Richard\_Marquez](https://forum.inductiveautomation.com/u/Richard_Marquez)\ **Post date:** [June 8, 2024, 10:56pm UTC](https://forum.inductiveautomation.com/t/problem-s71500-driver/46306/4 "2024-06-08T22:56:44Z")
Similar problem, right now, on January 30 version (.37) - Error: BasicRequestCycle 08Jun2024 16:50:16 Exception caught during sendRequest(). ```python java.lang.IllegalArgumentException: Cannot get bytes for BuiltinDataType String. at com.inductiveautomation.xopc.driver.util.UAByteUtilities.fromVariant(UAByteUtilities.java:235) at com.inductiveautomation.xopc.drivers.siemens.util.S7ByteUtilities.getBytesFromVariant(S7ByteUtilities.java:220) at com.inductiveautomation.xopc.drivers.siemens.structs.converters.DefaultValueConverter.convertValue(DefaultValueConverter.java:44) at com.inductiveautomation.xopc.drivers.siemens.structs.writers.ValueBlockWriter.write(ValueBlockWriter.java:21) at com.inductiveautomation.xopc.drivers.siemens.structs.writers.S7WriteRequestDataWriter.write(S7WriteRequestDataWriter.java:20) at com.inductiveautomation.xopc.drivers.siemens.structs.writers.S7WriteRequestWriter.write(S7WriteRequestWriter.java:17) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest$1.write(WriteRequest.java:126) at com.inductiveautomation.xopc.drivers.siemens.protocols.TxPacket.(TxPacket.java:32) at com.inductiveautomation.xopc.drivers.siemens.protocols.ProtocolStack.transmit(ProtocolStack.java:23) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest.buildPacket(WriteRequest.java:123) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest.preparePacket(WriteRequest.java:112) at com.inductiveautomation.xopc.drivers.siemens.requests.WriteRequest.sendMessage(WriteRequest.java:105) at com.inductiveautomation.xopc.driver.api.AbstractDriver$AdhocRequest.sendMessage(AbstractDriver.java:1284) at com.inductiveautomation.xopc.driver.api.BasicRequestCycle$PendingRequest.sendMessage(BasicRequestCycle.java:415) at com.inductiveautomation.xopc.driver.api.BasicRequestCycle.sendRequest(BasicRequestCycle.java:230) at com.inductiveautomation.xopc.driver.api.BasicRequestCycle.run(BasicRequestCycle.java:148) at java.base/java.lang.Thread.run(Unknown Source) ```