motionCAT Glossaries

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Master Board

This is the board in which the center device is installed. Communications of the motionCAT system is controlled with this board.


Lines include the serial communication line, communication line, and the transmission line of the center device.
In addition, the ID number of the center device line installed in the master board is called the line number.


A slave is a unit composed of a communication board and multiple modules (1 to 6 modules). There are two types; HMG type and HUG type.


Lines include the serial communication line, communication line, and the A module is the circuit board for assembling a slave. Modules include motion (P, C), DIO (D, T), and analog (A) modules.
Each of them is identified by a module ID. Module IDs can be set from 00h to 3Fh (0-63).

Module ID

A module ID is an address (ID) to identify each module. It is set with the M ID rotary switch on the communication board.

System Communication and Local Device Information

This is a communication to retrieve the connection status, device type, and input/output port settings of each local device. These pieces of information on local devices are called the local device information.

Cyclic Communication

In Motionnet communications, the center device always controls the communication line.
Each local device can transmit only when allowed by the center device.
The center device communicates with each connected local device sequentially, beginning with that having the lowest numbered module ID.
The center device starts by establishing a communication with the first local device. Over the communication line (one line), there is only one device that can receive this communication (there must not be duplicated module IDs).
The local device that received the communication is the next to have the right to use the communication line, which will be used for a communication from the local device to the center device. This constitutes one set of communications.
The center device establishes similar communications with all of the local devices in the order of module IDs.
This communication that is started again from the module with the lowest ID when the communication with the module with the last ID finishes is called cyclic communication.

Data Communication

Data communication is used to send commands to operate motion devices.
Data communication is performed by interrupting the cyclic communication at any time (when a command is sent from the software).
The following figure shows an example of cyclic communication sequence.

The arrow in the figure represents the sequence in cyclic communication. If a data communication command is issued at [A], it becomes as follows:

Although the time required for one cyclic communication is extended, the data exchange with the target device can be performed promptly.
In data communication, as in cyclic communication, a response communication is transmitted to the center device from the local device that has received data.

Note:Data communication is performed "at any time" as mentioned above, yet within the following constraint: One cyclic communication must be inserted when performing consecutive data communications or retrying a data communication due to a communication error.
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