GE Genius Communications

ORION supports a variety of popular Ethernet I/O products in motion control applications. Fully integrated software includes The GE Genius MotionBASIC® Extension provides peer-to-peer data and I/O communications between processors on a GE Genius factory network. I/O communications are supported for any device that supports Global Data. The I/O Adapters ORN-GE1 and ORN-GE2 provide the ORION® controller connectivity to a GE Genius Bus for Global Data and Datagram communication to the Series 90-70 and Series 90-30 PLC bus controllers.

Global Data and I/O Operation

All data on the I/O Adapter is global to the network. The I/O Adapter interface module will automatically refresh all global data on the bus it is linked to. The process of accessing data in this manner has minimal effect on the user’s program execution time because monitoring and participating in the scanning process is the responsibility of the I/O Adapter interface ORN-GE1/GE2.

The MBX-GE software product extends MotionBASIC® to provide methods to read global data on the I/O Adapter by accessing the data as a simple array. To read data belonging to an another station on the bus, the station’s address and a table position are used to index the array pointing to the data being read.

MBX-GE allows data is be accessed as a single bit or as a 16 bit word integer.

Data writes are performed on a local table of physical memory which is global to all other stations on the bus.

The single channel Network I/O Adapter (ORN-GE1) buffers all global data on one bus of a GE Genius factory network to provide all stations on that quick access to a common database between CPUs and I/O connected to that bus.

The dual channel interface ORN-GE2 allows one ORION® controller to communicate on two separate GE Genius bus systems.

PLC Register Availability

To access GE PLC registers the ORN-GE1/GE2 I/O Adapters use the datagram transfer method which involves some programming on the part of the user to start a datagram transfer and monitor the status to assure the transfer is complete before using the data. The datagram transfer method may be slower than Global Data table access when the data being transferred is long enough to be divided into multiple parts and transferred using multiple scan cycles of the bus. This method is a messaging service which provides an advantage -- the amount of data can vary allowing the user to specify the number of registers that are transferred in one datagram. The MotionBASIC® language, when extended with the MBX-GE, will include language statements to initiate, control, and monitor the datagram transfer for reading and writing to PLC registers over a GE Genius network bus.

Communication Bus Scan Rate

Access to Global Data is immediate, but age of the data is determined by the scan rate of the bus. The physical architecture of the network topology determines its scan rate. A scan completes the process of reading and writing data to the buffers of all stations linked to the network bus. The total time to scan all stations on the bus includes a refreshing operation on each station buffer plus the time it takes to transfer data from one station or I/O block to the next. The data transfer time is related to the baud rate of the bus.

The length of cable used to connect stations and amount of data per I/O block on a bus sets the maximum baud rate to ensure reliable communications. Increasing the number of stations and/or increasing the length of cable between stations will increase the scan time for one cycle increasing the update time of data on that network.

Typical scan times for a bus operating at 153.6K baud range from 3 milliseconds for one I/O block to 50 milliseconds for 31 I/O blocks and stations with a cable length of 2000 feet. Splitting up a loaded slow network into two buses will balance the scanning load, providing optimum response for the total system by placing the time-critical I/O on one bus and communications on the other.

The dual channel I/O adapter (ORN-GE2) provides the ORION® controller with a convenient method for operating on two separate network buses.

Built-in Diagnostics

The MBX-GE provides an extensive list of diagnostic features accessible to the user’s program that include real-time status variables, counters that record bus communications activity, interrupts to service critical faults, and datagram transfer status. Additional commands at the user level will output information to a window in MotionDesk 2.0, presenting the current configuration, bus, and datagram activity of the ORN-GE1/GE2.

Physical Layer

The physical layer is typically a daisy-chained bus cable, single twisted pair plus shield or Twinax (Fiber is an option). The bus is terminated at both ends. The maximum bus length is baud rate dependent. The baud rate ranges from 38.4K baud to 153.6K baud. The bus supports up to 32 devices (16 devices at 38.4K baud).

Protocol

The protocol is token passing with "implicit token" and "fast token recovery". The token passes on the bus from the lowest device ID to the highest ID. Each complete rotation is called a bus scan. The absolute minimum scan time is 3 msec. CRC checking is performed on each message. All devices perform a bus address conflict test at log-in time.

Installation

To install GE Genius® communications in an ORION® motion controller, simply:

• insert the desired communications adapter (either 1 or 2 channel) and connect the physical communications link;
• make sure the MotionBASIC® System Card containing the MBX-GE is installed by using the Upgrade Director in MotionDeskTM
• configure and test the interface, and;
• map register numbers to any MotionBASIC® variables containing data to be communicated over the network.

MBX-GE Language Extensions to access the GE Genius Bus

Field Control, Series 90 and Genius are trademarks of GE Fanuc Automation North America, Inc.

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