Black Box GEH-6510 manual Glossary of Terms DDE Server User’s Guide

Protocol Timer Tick – The time interval at which the Server executes DDE protocol; how often the Server listens for an incoming message from a device or transmits a message to a device.

Register – Location in a device’s memory containing a single binary datum. Each register has a particular address, and the DDE Server can access a register’s data by specifying the device and the register’s address. Mnemonics are used to make the numeric register addresses more meaningful; for example, VOLTS_A is understandable as the volts on phase A of a particular device, whereas the actual register address might be R10024-A1, which conveys no meaning to the reader.

Register Map – Comprehensive listing of all register addresses and what they contain.

Scan Interval – Defines how often a device is to be scanned under optimal conditions; this is a target time which may not be attained due to network traffic load, number of devices, amount of data being requested, etc. A scan interval of 1000 msec (1 second) indicates that the DDE Server will attempt to scan the device as close to once per second as it can.

Server – A DDE-compliant MS Windows application providing data to other DDE- compliant applications (clients) on their request.

Time-out– The error message generated when no reply is received to a query after a given period of time.

Topic – A user-defined name associated with a specific device set to be polled at a particular frequency.

Valid Data Time-out– The time (in milliseconds) that elapses after a client has made a request for data to the PMCS DDE Server before a time-out error message is returned to the client.

88 • Glossary of Terms DDE Server User’s Guide