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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Exception on forward.close after logging data with ENBT/A","articleBody":"**Pre-checks**\r\n- [x] running latest version \r\n- [x] enabled logging \r\n- [x] consulted the [docs](https://pycomm3.readthedocs.io/en/latest/) \r\n\r\n**Description**\r\nI'm running a long (hours) datalogger using pycomm3 sometime when I close the connection  (PLC.close()) it will report a parse replay failure on the forward_close(). Seems to happen more often after running for a longer (\u003e10 minutes) time. The datalogger will read a set of tags. And when I interrupt it using \u003cctrl-c\u003e the exception instructs pycomm3 to close the connection.\r\n\r\n**Target PLC**\r\nModel:  1756-L73\r\nFirmware Revision: 32.11\r\nOther Devices in CIP Path:  1756-ENBT/A v 5.006\r\n\r\n**Code Sample**\r\nStripped back to minimal\r\n\r\n```\r\nfrom pycomm3 import LogixDriver\r\nimport logging, time, datetime\r\nfrom pycomm3.exceptions import RequestError\r\n\r\nPLCAddress = 'PC15'\r\nPLC = LogixDriver(PLCAddress, init_program_tags= False)\r\nPLC.open()\r\nprint(PLC.info)\r\nlogging.info('Connected')\r\npacktags = 'A15S1_PackData','A16S1_PackData','A16S1S3_PackData','A16S3_PackData','A16S3S4_Packdata','A16S4_PackData','A16S4S5_Packdata','A16S5_PackData','A17S1_PackData','A17S2_PackData','A17S3_PackData'\r\ntry:\r\n    logging.info('Reading')\r\n    while True: # and ChangeCount \u003c 3:\r\n        for tagname in packtags:\r\n            packdata_i = PLC.read(tagname)\r\n            print('*' , end = '')\r\n        time.sleep(1)\r\n\r\nexcept KeyboardInterrupt:\r\n    pass\r\n\r\nexcept Exception as err:\r\n    logging.exception(err)\r\n    \r\nfinally:\r\n    logging.info('Disconnecting')\r\n    PLC.close()\r\n\r\n```\r\n\r\n**Additional context**\r\nOutput from DEBUG logging:\r\n```\r\n2024-07-25 07:22:30,514 Sending generic message: forward_close\r\n2024-07-25 07:22:30,515 Sent: GenericUnconnectedRequestPacket(message=[b'N', b'\\x02 \\x06$\\x01', b\"\\n\\x05'\\x04\\t\\x10\\xbd\\xea\u003eq\", b'\\x03\\x00\\x01\\x00 \\x02$\\x01'])     \r\n2024-07-25 07:22:30,520 Failed to parse reply\r\nTraceback (most recent call last):\r\n  File \"C:\\Users\\plompt\\AppData\\Local\\Programs\\Python\\Python311\\Lib\\site-packages\\pycomm3\\cip\\data_types.py\", line 156, in encode\r\n    return cls._encode(value)\r\n           ^^^^^^^^^^^^^^^^^^\r\n  File \"C:\\Users\\plompt\\AppData\\Local\\Programs\\Python\\Python311\\Lib\\site-packages\\pycomm3\\cip\\data_types.py\", line 216, in _encode\r\n    return pack(cls._format, value)\r\n           ^^^^^^^^^^^^^^^^^^^^^^^^\r\nstruct.error: ubyte format requires 0 \u003c= number \u003c= 255\r\n\r\nThe above exception was the direct cause of the following exception:\r\n\r\nTraceback (most recent call last):\r\n  File \"C:\\Users\\plompt\\AppData\\Local\\Programs\\Python\\Python311\\Lib\\site-packages\\pycomm3\\packets\\ethernetip.py\", line 127, in _parse_reply\r\n    self.service = Services.get(Services.from_reply(self.raw[40:41]))\r\n                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\r\n  File \"C:\\Users\\plompt\\AppData\\Local\\Programs\\Python\\Python311\\Lib\\site-packages\\pycomm3\\cip\\services.py\", line 99, in from_reply\r\n    val = cls.get(USINT.encode(USINT.decode(reply_service) - 128))\r\n                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\r\n  File \"C:\\Users\\plompt\\AppData\\Local\\Programs\\Python\\Python311\\Lib\\site-packages\\pycomm3\\cip\\data_types.py\", line 158, in encode\r\n    raise DataError(f\"Error packing {value!r} as {cls.__name__}\") from err\r\npycomm3.exceptions.DataError: Error packing -128 as USINT\r\n```\r\n\r\n\r\n","author":{"url":"https://github.com/tcplomp","@type":"Person","name":"tcplomp"},"datePublished":"2024-07-24T20:12:55.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/319/pycomm3/issues/319"}