Omron NT631C manual Communications Using Memory Links, Connecting to Other Companies’ PLCs

Communications Using Memory Links Section 1-5

The NT link is compatible with the host link. The NT631/NT631C screen data and PLC programs used with the host link direct connection method can be used with the NT link method as they are.

1-4-4 Connecting to Other Companies’ PLCs

	Installing a system program for multi-venders by using a specific system
	installer enables the NT631/NT631C to be connected to the PLCs of other
	models in direct connection. This system installer is supplied with the Support
	Tool (NT-ZJCAT1-EV4).
Compatible PLC	The NT631/NT631C can be connected to the following model PLCs.

• Mitsubishi A-series programmable controller (computer link module)

• Mitsubishi FX-series programmable controller

• SLC 500 Series by Allen-Bradley

• 90-20 and 90-30 Series by GE Fanuc

• S7-300 and S7-400 Series by Siemens

For details on the procedure for connecting to other model PLCs, refer to the

PLC Connection Manual or NT31/631 Multi Vendor Connection Manual.

1-5 Communications Using Memory Links

In this section, a communications method other than the direct connection, called the memory link, is discussed.

1-5-1 Memory Link

Memory link is a method to send and receive data between a personal com- puter or a FA computer and the NT631/NT631C by using RS-232C/422A communications.

In memory link, there is an area called PT Memory, as shown below, inside the NT631/NT631C, and this area is treated as a virtual area on the PLC. This allows PT memory and the display elements of the NT631/NT631C to make a quasi-direct connection. By sending a command for the memory link, the host can make the NT631/NT631C execute processes through PT memory. Fre- quently used commands are kept handy for read and write tasks of the numeral memory table, character-string memory table, and bit memory table.

PT

PT memory

Numeral memory table

Lamp

Direct connection

RS-232C/422A communications

In the memory link method, the only difference is that the NT631/NT631C finds its communications target inside instead of outside. In the memory link method, therefore, change of the target is all that is needed to be capable of using the exact screen data that is acquired by the direct connection. (With the NT631/NT631C, the Support Tool must be used to convert the data to screen data for the memory link.)

When compared to the direct connection of the host link or NT link methods, the memory link method has some restrictions regarding the use of some functions, as described below.

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