the Modbus network.
Many host SCADA packages support the Modbus
protocol, while devices commonly supporting the
protocol include several PLCs, as well as many other
third party devices in the marketplace. (For a partial list
of devices that speak Modbus, please visit the ProSoft
Tested section of the ProSoft Technology web site).
General Specifications
• Single Slot – 1756 backplane compatible
• Local or remote rack
• The module is recognized as an Input/Output
module and has access to processor memory for
data transfer between processor and module
• Ladder Logic is used for data transfer between
module and processor.
• Configuration data obtained through user-defined
ladder. Sample ladder file included
Functional Specifications
Some of the general specifications include:
• Support for the storage and transfer of up to 5000
registers to/from the ControlLogix processor's data
files
• Module memory usage that is completely user
definable
• Two ports to emulate any combination of Modbus
master or slave device
• Supports Enron version of Modbus protocol for
floating point data transactions.
Slave Specifications
The MVI56-MCM module accepts Modbus function code
commands of 1, 2, 3, 4, 5, 6, 8, 15, 16, 17, 22 and 23
from an attached Modbus master unit. A port configured
as a Modbus slave permits a remote master to interact
with all data contained in the module. This data can be
derived from other Modbus slave devices on the
network, through a master port, or from the ControlLogix
processor.
Master Specifications
A port configured as a virtual Modbus master device on
the MVI56-MCM module actively issues Modbus
commands to other nodes on the Modbus network. One
hundred (100) commands are supported on each port.
Additionally, the master ports have an optimized polling
characteristic that polls slaves with communication
problems less frequently. The ControlLogix processor
can be programmed to control the activity on the port by
actively selecting commands from the command list to
execute or issuing commands directly from the ladder
logic.
Additional Products
ProSoft Technology offers a full complement of
