Data Highway/Plus Communications

The Data Highway/Plus adapter and MotionBASIC Extension (MBX) allow ORION motion controllers to communicate using Allen-Bradley’s Data Highway or Data Highway Plus network protocols. The Data Highway and Data Highway Plus factory data transfer networks provide a convenient and powerful method for data communications between ORION motion controllers, programmable logic controllers, man-machine interfaces, host computers and other intelligent devices which support them.

Data Highway and Data Highway Plus Architectures
Allen-Bradley’s Data Highway network is a 57.6 K-Baud peer-to-peer message passing network which uses a floating master scheme. This approach makes it suitable for large networks of up to 256 devices. Data Highway Plus is a token-passing peer-to-peer network suited to systems with less than 20 stations. Data Highway Plus can operate at 57.6 K-baud or 115.2 K-baud. Because of its orientation and performance, Data Highway Plus is normally the best choice for use with ORION motion controllers.

The physical layer for both Data Highway and Data Highway Plus is implemented with factory-hardened, synchronous serial communications hardware and twin-axial cable. An ORION motion controller with a Data Highway/Plus MBX supports one Data Highway or Data Highway Plus port using the associated communications adapter which plugs into the ORION backplane. The communications adapter provides the physical network interface and contains a co-processor for performing network communications. It communicates with the main processor through a shared memory interface.

Installation
To install Data Highway/Plus communications in an ORION motion controller, simply:
insert the communications adapter and connect the physical communications link;
make sure the MotionBASIC System Card containing the Data Highway Plus MBX is installed
configure and test the interface, and;
map register numbers to any MotionBASIC variables containing data to be communicated over the network.

Operation
Data Highway and Data Highway Plus are Factory Data Communications Networks and, as such, require you to map register numbers to the MotionBASIC variables containing data to be communicated over the network. Once mapped, both ORMEC pre-defined variables and user variables can be transferred. All Data Highway and Data Highway Plus communications are handled in the background by the co-processor and have minimal impact on your MotionBASIC program operation. Data Highway and Data Highway Plus can be used to transfer both integer and floating point data between devices on the network.

Initiating Data Highway or Data Highway Plus Messages
ORION motion controllers can initiate Data Highway/Data Highway Plus commands as documented in the chart below. Data sent or received by these commands is obtained from, or loaded into, registers that are mapped to MotionBASIC program variables.

Responding to Data Highway or Data Highway Plus Messages
ORION motion controllers can also respond to the Data Highway and Data Highway Plus messages listed in the chart below. The Unprotected Read and the Unprotected Write functions can transfer up to 90 registers per transaction. The Typed Read and Typed Write functions can transfer up to 90 integers or 45 floating point variables. Data received or returned by Data Highway and Data Highway Plus functions is loaded into, or obtained from, registers that are mapped to MotionBASIC program variables. All Data Highway and Data Highway Plus message responses occur in the background and is transparent to your MotionBASIC program. In addition, Data Highway/Plus message response communications are configurable to allow any change to certain registers made over the network to trigger a specified subroutine. This feature makes it easy for a Data Highway/Plus master to initiate an action to be taken by any ORION motion controller connected to the Data Highway or Data Highway Plus network. 

Functions Supported by ORION

Data Highway/Plus Commands initiated by ORION:

¹ Both logical binary and logical ASCII address modes are supported.
² Use Unprotected Read/Write to send these commands

Data Highway/Plus Commands initiated by ORION:

¹ Both logical binary and logical ASCII address modes are supported.
² Use Unprotected Read/Write to send these commands.
³ The ORION motion controller performs no action other than returning a status of 0 when it receives this command.

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