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Application Guide | iC2-Micro Frequency Converters
The bus reference is commonly used for speed control. It is also possible to access the parameters, read their values, and, where possible,
write values to them. Accessing the parameters offers a range of control options, including controlling the setpoint of the drive when its
internal PI controller is used.
Network Configuration
6.1.7.3
To enable the FC protocol for the drive, set the following parameters.
Table 31: Parameters to Enable the Protocol
Parameter
P 10.1.1 Protocol
P 10.1.2 Address
P 10.1.3 Baud Rate
P 10.1.4 Parity/Stop Bits
Modbus RTU Message Framing Structure
6.1.7.4
Modbus RTU Message Byte Format
6.1.7.4.1
The controllers are set up to communicate on the Modbus network using RTU (remote terminal unit) mode, with each byte in a telegram
containing 2 4-bit hexadecimal characters. The format for each byte is shown in the following tables.
Table 32: Format for Each Byte
Start bit
Data byte
Table 33: Byte Details
Coding system
Bits per byte
Error check field
Modbus RTU Telegram Structure
6.1.7.4.2
The transmitting device places a Modbus RTU telegram into a frame with a known beginning and ending point. This allows receiving
devices to begin at the start of the telegram, read the address portion, determine which device is addressed (or all devices, if the
telegram is broadcast), and to recognize when the telegram is completed. Partial telegrams are detected and errors set as a result.
Characters for transmission must be in hexadecimal 00–FF format in each field. The drive continuously monitors the network bus, also
during silent intervals. When the 1st field (the address field) is received, each drive or device decodes it to determine which device is
being addressed. Modbus RTU telegrams addressed to 0 are broadcast telegrams. No response is allowed for broadcast telegrams. A
typical telegram frame is shown in the following table.
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8-bit binary, hexadecimal 0–9, A–F.
2 hexadecimal characters contained in each 8-bit field of the telegram.
• 1 start bit.
• 8 data bits, least significant bit sent first.
• 1 bit for even/odd parity; no bit for no parity.
• 1 stop bit if parity is used; 2 bits if no parity.
Cyclic redundancy check (CRC).
Setting
Modbus
1–247
2400–115200
Even parity, 1 stop bit (default)
AB413939445838en-000301 / 130R1254 |
Stop/
Stop
parity
85
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