ALPHA6000 and ALPHA6000S/V frequency converters all have built-in RS485 communication protocol, and all are built-in on the hardware, as standard configuration. Therefore, the communication function can be enabled at any time. However, during the use, the customer also encounters the situation that communication is not possible. He often calls to ask whether the inverter has a standard communication function and whether 485 communication follows the modbus protocol. This requires our patience to explain to customers.
1. Problem description
ALPHA6000 and ALPHA6000S/V frequency converters all have built-in RS485 communication protocol, and all are built-in on the hardware, as standard configuration. Therefore, the communication function can be enabled at any time.
However, during the use, the customer also encounters the situation that communication is not possible. He often calls to ask whether the inverter has a standard communication function and whether 485 communication follows the modbus protocol. This requires our patience to explain to customers.
2. Reason analysis
1. ALPHA6000 and ALPHA6000S/V inverters only support instructions 03, 06 and 10, and only support one byte read and write. Multi-write, multi-read, inverter does not support. Use text screen or touch screen, because the choice of communication mode is wrong, it may not send the specified command 03,06,10, but other commands, such as 04, etc., may also issue commands to read and write 2 words, these frequency conversion The device is not responding.
2. The communication format is wrong, and the data not sent according to the modbus protocol specification is usually a CRC check error.
3. The PLC or host does not set the same baud rate, communication address and parity as the inverter.
4. If the communication line is disconnected or reversed, CCF6 failure is reported, and communication is prohibited.
5. The communication command is not issued. If you write a PLC program, there is no PLC timing condition or terminal closing and sending condition, and the communication command has not been executed.
6. Inverter under voltage or data write protection.
7. The written data exceeds the upper and lower limits, and the inverter does not accept it.
8. The parameters written in the text screen or PLC cannot be saved.
3. Solution measures and result evaluation
Corresponding to the cause analysis, the following measures can be taken
1. Inform the customer that the Alpha frequency converter follows the modbus protocol. Because it is streamlined, it currently supports only 1 word to read and write, and the instructions can be 03,06,10 instructions. Other instructions are temporarily not supported.
2. Use the correct command format to calculate the CRC and send out the data.
3. Modify the inverter parameters so that the host and the inverter, baud rate, address, parity, 3 unified
4. Check the line and confirm that the communication line is normal and not reversed; press STOP to reset the CCCF6 fault and restore the communication function.
5. Check the PLC program to ensure that the communication data can be sent out and the format is correct.
6. Ensure that the voltage is normal or that the PF.01 parameters are not write-protected. Parameters that cannot be modified during operation cannot be modified but can be read.
7. Check the sent data, in the manual, within the parameter setting range. Do not exceed the upper and lower limits.
8. All written communication parameters are not saved by default in the inverter. However, the user can use the No. 10 instruction to write the saved modbus address to 0x00FF, and the parameters can be written to the EEPROM of the frequency converter without loss of power. Because the text screen cannot automatically write the address corresponding to the data to be saved to 0x00FF, the data cannot be saved. This limitation mainly prevents the host from continuously writing EEPROM and invalidating the EEPROM. If the customer needs it, it can be customized, and the parameters can be directly written into the inverter with a text screen, and it will not be lost even if it is powered off. 6500 series special frequency converter for rotary cutter can be directly modified and saved.