Setup
Document No. D106-009
Page 29 of 76
Revision 1.15
The second part of the Reactive Tag mode is to configure the link between a Modbus function
and register range to a Logix tag. This will allow the Modbus message initiator to effectively
write to, or read from, a Logix tag using traditional Modbus functions.
Figure 3.20 – Reactive Tag Mapping (Logix Controller Type)
Modbus read and write functions involve the transfer of either Booleans or integers (16 bit).
A part or combination of integers may represent other types. For this reason, the Modbus
Router allows the mapping of integer based functions to the following Logix data types when
using a ControlLogix or CompactLogix controller:
SINT
INT
DINT
REAL
All discrete or Boolean based function need to be mapped to a Logix BOOL array.
NOTE
: When mapping a range of registers to a Logix array, it is important to
ensure that the destination Logix array is sufficiently large to accommodate all
the data.
NOTE
: When mapping a range of registers to a Logix DINT or REAL array, the
Register Start must be an even number, else the integer data will not be
aligned with the 32-bit destination Logix tag.
NOTE
: When writing to a DINT or REAL datatype the user cannot write a single
Modbus element (16-bit). At least two elements will need to be written to
either of the above 32-bit datatypes (DINT or REAL).
