Omron NT31 NT31C manual Comparison between Direct Connection and Memory Link

Communications Using Memory Links Section 1-5

Screen switching strobe

Numerals input strobe

Character-string input strobe

•The usable area for allocation is the PT memory only.

1-5-2 Comparison between Direct Connection and Memory Link

The major differences between the direct connection and the memory link are as follows:

•In the memory link method, the communication with the host should be carried out by using commands. Compared to the ordinal direct connection, which can be used requiring almost no programs, the memory link method requires a pro- gram that is necessary for interchange of commands. This, however, gives ad- vantages to the memory link method by using a large variety of functions avail- able in the direct connections from major models such as a personal computer and a FA computer equipped with RS-232C/RS-422A communication means, allowing the PT to be suited for larger usage.

•Actual PCs have many kinds of areas, where as PT memory is a single area with only one kind. When creating screen data by using the memory link meth- ods, it is always necessary to allocate display parts in the PT memory.

For communication between the host and the PT by the memory link method and for handling screen display elements, refer to the NT31/NT31C/NT631/NT631C Programmable Terminal Reference Manual.

1-5-3 Memory Link Online Transfer Function

When memory link communications are being used, the NT31/NT31C can be switched to Transmit mode from the host even if the NT31/NT31C is operating and screen data can be written. (The NT31/NT31C can be returned to RUN mode after the screen data is written.)

The memory link online transfer function can be used to replace screen data at a fixed time each day or replace screen data with maintenance screen data for maintenance.

For more details on the memory link online transfer function, refer to information on the memory link online transfer function in the NT31/NT31C/NT631/NT631C Programmable Terminal Reference Manual.

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