I am attempting to retrieve the energy meter reading from the 4405 Model L&T using RS485 communication protocol with a Delta PLC 12sa2.
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I am utilizing an L&T 4405 energy meter connected via RS485 communication through a PLC. The data address for R Phase Voltage is 40143, and I am using the Modrw command to communicate. However, I am receiving values in a different format than expected. Can you assist me in converting these values into float format? I have included the program for reference.
In Mitsubishi PLCs, floating point numbers are represented using two 16-bit registers for single precision and four registers for double precision. To access the value (assuming single precision float), use the instruction EMov D103 to D200 to store it in a 32-bit register. Keep in mind that in Modbus communication, word or byte swapping may be necessary if the value is not displayed correctly. Additionally, some Modbus registers may be offset by one byte or word, so adjustments may need to be made.
Thank you for responding. I am currently utilizing a Delta PLC model DVP12sa211r able to access voltage readings for the RYB phase through the COM2 modrw command D1296-D1311. By using registers D1296-D1311, I am able to read up to 9 data addresses. However, I am interested in retrieving all 28 data addresses available. I have uploaded images of the datasheet and program for reference.
One effective method is to conduct polling in groups of 4, utilizing a counter that resets after reaching a count of 7. By comparing the counter to initiate the reading of relevant registers, transactions can be efficiently stored in the necessary location upon receipt. This approach ensures systematic data handling and processing.
You'll need a RS485 connector, such as a Modbus converter, to establish communication between your 4405 Model L&T Meter and Delta PLC 12sa2. Make sure that both are compatible with RS485 Modbus protocol. Initial settings like baud rate, parity, and stop bits in the PLC and energy meter should match accurately. Your PLC program should be configured to send read command for the specific register on the energy meter which holds the data you want to fetch. It might be best to first test your RS485 network with a small example before implementing your main program.
You might want to look into Modbus-RTU protocol for this task, as it's the most commonly used communication protocol over RS485. Just ensure that both your energy meter and PLC are set to the same baud rate and parity. You'll also need to know the register address in the energy meter from where you want to read the data. Furthermore, use a converter if your PLC doesn't support RS485 natively.
Sounds like a fascinating project. Have you tried using a MODBUS RTU protocol? It's a well-accepted method for PLC to communicate with various devices, and the 4405 Model L&T energy meter supports it. Also, make sure your PLC and energy meter are set at the same baud rate for proper synchronization.
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Answer: Answer: The communication protocol used in this case is RS485.
Answer: Answer: You can interface the Delta PLC 12sa2 with the L&T 4405 Model using RS485 communication protocol.
Answer: Answer: Yes, ensure that the RS485 communication settings are properly configured on both the Delta PLC 12sa2 and the L&T 4405 Model for successful data retrieval.
Answer: Answer: Yes, once the energy meter readings are successfully retrieved, they can be utilized for monitoring and control applications within a larger system integrated with the Delta PLC 12sa2.
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