User`s guide

MBX Driver Help
Cyberlogic Technologies Inc. - 9 -
COMMUNICATION USING THE MBX DRIVER
Modbus Plus is a 1 Mbit/sec peer-to-peer communication network. Its architecture
supports both solicited (Master Path) and unsolicited (Slave Path) communications. It
also supports global data and Peer Cop communications.
The message structure used by Modbus Plus is identical to the older Modbus message
structure with the exception of the destination node address. Modbus Plus uses a 5-byte
routing path to identify the destination node versus the 1-byte destination node
addressing of Modbus. Also, a local network is limited to 64 nodes.
Modbus Plus is the most common of the Modicon networks and, therefore, has the best
support in third-party automation software products. Many of these products
communicate through the NETLIB library, which is well-supported on both 16-bit and 32-
bit platforms.
For more information on Modbus Plus, refer to Modicon IBM Host Based Devices User's
Guide from Schneider Electric (Order #890 USE 102 00).
Main Driver Features
The kernel mode device driver of the MBX Driver supports all current Modbus Plus
interface adapters for PCI, ISA, EISA, MCA, PCMCIA and USB buses. Multiple interface
cards can be installed at the same time, limited only by the number of available slots.
Each adapter card can operate in either interrupt or polled mode.
The driver supports all Modbus Plus features including support for Data Master/Slave,
Program Master/Slave, Global Data and Peer Cop. The high-performance native API of
the MBX Driver is designed to take full advantage of the event-driven, multitasking,
multithreaded features of Windows. For legacy applications, a simpler NETLIB interface is
also provided.
Modbus Plus Routing Paths
Message routing over Modbus Plus is achieved through the use of a five-byte routing
array. Each byte in the array specifies the node address of a bridge, a destination node
or a path within a host-based adapter. Here are a few examples to illustrate this concept.
Routing to a Local Programmable Controller
A typical routing to a programmable controller on the local network would look like this:
23.0.0.0.0. This indicates that the message should go to the programmable controller at
node 23. The zeros indicate that no further routing is needed.
Routing Through Bridges
If you want to route the message through a bridge to a programmable controller on
another network, you must specify the node address of the bridge,then the address of