Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 125)

Publication AG-UM008C-EN-P - February 2005
Configuring MicroLogix 1100/1200/1500 Controllers 3-57
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)
Local file types must be Binary (B) or Integer (N) for Modbus
commands. In addition, 32-bit holding register commands (3 and 16)
allow Floating Point (F) and Long (L) local file types.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 defaults to 1. For coil/input commands (1, 2, 5 and
15), elements are in bits. For 16-bit register commands (3, 4, 6 and
16), elements are in words. For 32-bit holding register commands (3
and 16), elements are 32 bits long.
Target Device
Message timeout is specified in seconds. If the target does not respond
within this time period, the message instruction will generate a
specific error. 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.
The default Modbus Data Address is 1. The Range is 1 to 65,536.
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).