Allen-Bradley MicroLogix 1100 Instruction Set Reference Manual page 371

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Data Table Address/Offset
This variable defines the starting address in the target controller. The data
table address is used for a 500CPU and PLC5 type messages. A valid
address is any valid, configured data file within the target device whose
file type is recognized by the controller. Valid combinations are shown
below:
Message Type
500CPU and PLC5
500CPU, PLC5 and 485 CIF
(1) Message Type must be 500CPU or PLC5. The Local File Type and Target File Type must both be Floating Point.
(2) 500CPU write RTC-to-Integer or RTC-to-RTC only.
(3) MicroLogix 1100 OS Series B FRN 4 or later
The data table offset is used for 485CIF type messages. A valid offset is
any value in the range 0 to 255 and indicates the word or byte offset into
the target's Common Interface File (CIF). The type of device determines
whether it is a word or byte offset. MicroLogix controllers and SLC
processors use word offset; PLC-5 and Logix processors use byte offset.
Modbus - MB Data Address (1-65536)
Modbus addressing is limited to 16 bits per memory group, each with a
range of 1 to 65,536. There are four memory groups, one for each
function:
• coils (generally addressed as 0xxxx)
• contacts (1xxxx)
• input registers (3xxxx)
• holding registers (4xxxx)
Coils and contacts are addressed at the bit level. Coils are outputs and can
be read and written. Contacts are inputs and are read-only.
Communications Instructions
Local File Type
(1)
O, I, B, N, F , L
T
C
R
(2)
RTC
(3)
ST
Publication 1763-RM001B-EN-P - April 2007
371
Target File Type
(1)
O, I, S, B, N, F , L
T
C
R
N, RTC
(3)
ST