I am looking for a way to convert 2 Integer registers into a Real format. These integers are sourced from Modbus registers holding a floating point value, and I need to convert them into a REAL register in my ControlLogix L71 PLC. Can someone help me with this conversion process?
Are you wondering if the registers in an integer array are consecutive? Take a look at the COP instruction in Logix, which allows for a bit-by-bit copy from the source to the destination. The length parameter specifies the number of elements in the destination. If your Modbus data is stored in 2 consecutive 16-bit elements within an array named "ModbusData" of type "INT[2]," follow these steps: COP Source: ModbusData[0] Destination: RealTag Length: 1 If the result seems unusual, refer to the datasheet of the device you are receiving data from to determine the byte/word order. Alternatively, analyze the bit patterns or try trial-and-error with byte swaps and word swaps (or a combination of both) until the data aligns correctly.
In order to properly match up byte swaps and word swaps, it may be necessary to undergo a trial-and-error process. This method can be quicker than attempting to solve the issue analytically. It is important to have at least one known float value in the device to experiment with. If you are receiving single-register values from the device, be aware of a potential off-by-one issue that could lead to inaccurate float conversions, resulting in a margin of error of approximately one percent.
You might want to take a look at the COP instruction in ControlLogix, it can handle this type of data conversion. Typically, your two integers, sourced from Modbus, would sit in an array of INTs. Use the COP instruction to copy this array into a DINT, then again copy it into a REAL data type. This step converts the raw integer data into a floating-point real number. However, depending on the endianness of your data, you may need to swap the order of the INTs in the array before the copy operation.
Sure, you can utilize the COP instruction for this conversion. If your two integers are housed in INT[0] and INT[1], for example, you'll want to COP these into your destination REAL register. In the COP instruction, source would be your INT[0] and your destination would be the REAL array, it is also necessary to specify a length of 2 for proper conversion. However, ensure you are not operating on this real register while performing the copy, otherwise, you may encounter an issue.
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Answer: 1. How can I convert 2 Integer Modbus Registers to Real in a ControlLogix L71 PLC? - To convert 2 Integer Modbus Registers to Real in ControlLogix L71 PLC, you can use a conversion process that involves combining the two integer values to form a floating-point value. This can be achieved by following specific steps or using mathematical operations in the PLC programming environment.
Answer: - The process involves extracting the two integer values from the Modbus registers, combining them to form a floating-point value, and then storing this floating-point value in a REAL register in the ControlLogix L71 PLC. This conversion ensures that the floating-point value is accurately represented in the PLC system.
Answer: - Yes, when converting Modbus Integer registers to Real in a ControlLogix L71 PLC, it is important to ensure that the integer values are extracted correctly, combined in the right order, and converted using appropriate data manipulation techniques to maintain accuracy and precision in the floating-point representation. Additionally, verifying the data types and formats in the PLC program is essential for successful conversion.
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