PLX30 Series
MBS Protocol
Ethernet and Serial Gateways
User Manual
ProSoft Technology, Inc.
Page 125 of 200
September 19, 2012
7.1.2 Modbus Master/Slave Port Specifications
Type
Specifications
General Parameters
Internal Database
Up to 4000 registers (words) available.
Communication parameters
Port 0: Baud Rate: 110 to 115K baud possible
110 to 38.4K baud recommended for all applications.
Higher baud rates are recommended only for use
with very slow Modbus polling rates (e.g. 1command
or less per second)
Port 1, 2, 3: Baud Rate: 110 to 115K baud
Stop Bits: 1 or 2
Data Size: 5 to 8 bits
Parity: None, Even, Odd RTS Timing delays: 0 to
65535 milliseconds
Modbus Modes
RTU mode (binary) with CRC-16
ASCII mode with LRC error checking
Floating Point Data
Floating point data movement supported, including
configurable support for Enron implementation
Modbus Function Codes
1: Read Coil Status
2: Read Input Status
3: Read Holding Registers
4: Read Input Registers
5: Force (Write) Single Coil
6: Preset (Write) Single Register
15: Force(Write) Multiple Coils
16: Force (Write) Multiple Register
Modbus Master
Command List
Up to 100 command per Master port, each fully
configurable for function, slave address, register
to/from addressing and word/bit count
Status Data
Error codes available on an individual command
basis. In addition, a slave status list is maintained
per active Modbus Master port.
Polling of command list
Configurable polling of command list, including
continuous and on change of data
Modbus Slave
Node address
1 to 247 (software selectable)
Status Data
Error codes, counters and port status available per
configured slave port starting at memory register
4400.
