S611 Soft Starter MN03902011E—May 2012 www.eaton.com 65
Appendix F—Network Communications (Modbus)
Modbus with IO Functionality
Modbus General Specifications
Note
Line polarization will reduce maximum number of devices by four.
Parameter Value
Mode Slave mode only
Byte characteristics RTU: 8 bit, even parity, 1 stop bit
ASCII: 7 bit, even parity, 1 stop bit
Slave response to master 10 ms plus the time it takes to transmit response (when applicable)
Commands supported 0x01 Read Coils
0x02 Read Discrete Inputs
0x03 Read Holding Registers
0x04 Read Input Register
0x05 Write Single Coil
0x06 Write Single Register
0x0F Write Multiple Coils (15)
0x10 Write Multiple Registers (16)
0x17 Read/Write Multiple Registers (23)
0x2B/0x0E Read Device Identification Get Device Identity (43/14)
Protocol supported ASCII or RTU
Electrical signaling RS-485 (ANSI/TIA/EIA-485), two-wire
Checksum CRC 16 bit 0x8005 (or CRC-CCITT 0x1021)
Maximum data signaling error accepted 2% in reception, 1% in transmission
Maximum number of devices
32 (1 unit load per RS-485)
LED indication Device busy
Maximum cable length Dependent on baud rate, cable characteristics (gauge, capacitance, or impedance), number of loads, 4000 ft
maximum theoretical. Reference Modbus-IDA over Serial Line Specification and Implementation Guide and
EIA-485 for details
Maximum number of writes to non-volatile memory Unlimited
Connector style Screw terminal
Network topology Two-wire Modbus, daisy-chain and/or repeater
Line polarization Not required. Reference Modbus over Serial Line Specification and Implementation Guide and EIA-485 for
more information
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