- Association: A logical link between two programmable devices over a network.
- Client: That half of an association which has sent a service request to another MMS-user.
- Confirmed Service: When a client sends a service request it receives a confirmation from the server as an acknowledgement that it was received. Note - Most MMS services are confirmed services; see negative and positive confirmation.
- Companion Standard: An extension of the MMS standard for a particular type of device or application.
- Domain: A subset of the functionality of the VMD, e.g. a part program or process parameter such as temperature readings.
- Event: A change of condition in a real device, e.g. when a temperature or pressure exceeds a pre-set value.
- Journal: A log file comprising a time-stamped record of notable activities. e.g. event or variable status.
- Manufacturing Automation Protocol (MAP): A set or profile of international standards for factory networking.
- Map; Mapped; Mapping: The process of defining the VMD to match the functionality of a real deviee.
- MMS-user: Any device that sends or receives MMS services.
- Negative Confirmation: lf the server cannot fulfil a service request sent out by a client, the client receives a negative confirmation.
- Open Systems: Open Systems is used to describe information systems with the following characteristics:
- the products used conform to relevant internationally agreed standards;
- the standards are non-exclusive, non-proprietary and vendor independent;
- applications can be moved as necessary between systems of different makes and sizes;
- usable information can be exchanged when required between different Systems.
- Positive Confirmation: lf the server can successfully fulfil a service request sent out by a client, the dient receives a positive comfirmation.
- Program Invocation (PI): An executable program which is composed of a set of domains.
- Profile: A set of functional standards selected to meet the requirements of an application.
- Real Device: A physical device that will do work, e.g. programmable logic controllers (PLCs), machine tools etc.
- Semaphore: A token passed between two or more devices and used for sharing a common resource.
- Server: That half of an association which responds to a service request.
- Service: An MMS service is a means of passing information between two MMS-users. They are used to manipulate the VMD and through it the real device.
- Service Request: When a dient sends a MMS message to a server.
- Unconfirmed Service: When a MMS user uses an unconfirmed service no confirmation is returned by the remote MMS user in the association. This service is used when confirmation is either undesirable (e.g. emergency situations) or unnecessary (e.g. information reporting).
- Variable: A data element that holds a value, e.g. the value of a temperature, or a set of temperatures, a count etc.
- Virtual Manufacturing Device (VMD): A software model of the functionality of a real deviee. The model maps directly onto the real device.