Allen-Bradley MicroLogix 1100 Instruction Set Reference Manual page 380

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380 Communications Instructions
Publication 1763-RM001B-EN-P - April 2007
"This Controller" Parameters
If a Channel configured for Modbus Master is selected in the Channel field
of the Message Setup Screen, the following Modbus Command options
will become available:
• 01 Read Coil Status (0xxxx)
• 02 Read Input Status (1xxxx)
• 03 Read Holding Registers (4xxxx)
• 04 Read Input Registers (3xxxx)
• 05 Write Single Coil (0xxxx)
• 06 Write Single Register (4xxxx)
• 15 Write Multiple Coils (0xxxx)
• 16 Write Multiple Registers (4xxxx)
Data Table Address
Local file types must be Binary (B) or Integer (N) for Modbus commands.
Starting data table address for coil/input bit commands (1, 2, 5 and 15)
require a bit address. Starting data table addresses for register commands
(3, 4, 6 and 16) require a word address.
Size in Elements
Size in elements defaults to "1". For coil/input commands (1, 2, 5 and 15),
elements are in bits. For register commands (3, 4, 6 and 10), elements are
in words.
Target Device
Message Timeout
Message timeout is specified in seconds. If the target does not respond
within this time period, the message instruction will generate a specific
error (see MSG Instruction Error Codes on page 414). The amount of time
that is acceptable should be based on application requirements and
network capacity/loading. A 2-second message timeout is generally
sufficient, as long as only one message is triggered at a time.
Modbus Data Address (decimal)
The default Modbus Data Address is 1. The Range is 1 to 65,536.
Slave Node Address (decimal)
The default Slave Node Address is 1. The Range is 0 to 247. Zero is the
Modbus broadcast address and is only valid for Modbus write commands
(5, 6, 15 and 16).