Omron NT631C manual Host Link NT Link, Features of the Direct Connection Function

Communications with the Host Section 1-4

Features of the Direct Connection Function

1-4-2 Host Link

1-4-3 NT Link

The words and bits allocated for direct connection are called the allocated words and allocated bits.

The direct connection function allows the data to be displayed at the NT631/ NT631C to be read from the memory area in the PLC and written to memory tables in the NT631/NT631C. Also, the data input at the NT631/NT631C can be written to the memory area in the PLC. The NT631/NT631C screen can be changed in accordance with statuses in the PLC memory area, and the NT631/NT631C’s status data can be written to the PLC’s memory area.

NT631/NT631C		PLC
	DM area		I/O relay area

Auxiliary relay area Timers/counters

The direct connection function has the following features.

•The bits and words referring to operating status and work instruction infor- mation and those for storing input data can be freely allocated to almost any area of the PLC memory.

•Since the NT631/NT631C can directly refer to PLC bit and word data with- out using the program at the PLC, it can be connected to the PLC without changing the PLC program which controls the currently running produc- tion line.

•The area to control and provide notification of the NT631/NT631C status, including display screens, display/no display status, and buzzer output, can be freely allocated to any part of the PLC data area. This means that the PLC status can be read and controlled just by reading this area at the PLC side, without preparing a special communications program.

The direct connection function allows the NT631/NT631C to directly read and write almost all bits and words in the PLC and to automatically change the NT631/NT631C screen display. This function can reduce the load on the PLC so that its program development efficiency is improved.

The host is connected to a PT in a 1:1 connection, and the words and bits of the host are read and displayed by host link communications. This method can be used for connection to the majority of PLC types.

NT link is a method for high-speed communications with a PLC using the direct connection function. The PLCs that can be connected with the NT link are as follows.

CPM1, CPM2A, CPM2C, CQM1, CQM1H, C200HS, C200HX/HG/ HE(-Z)E, CS1G/CS1H-E(V1), CS1D, CJ1G/CJ1H/CJ1M, CVM1/CV-series PLC (-EV1 or later version), SRM1

Besides the 1:1 NT link method, in which one PLC is connected to one PT, the NT631/NT631C can also use the 1:N connection NT link method, which allows a maximum of eight PTs to be connected to one PLC port.

PLCs that can be connected with the 1:N connection NT Link method are as follows: CQM1H, C200HX/HG/HE(-Z)E, CS1G/CS1H-E(V1), CS1D, CJ1G/ CJ1H/CJ1M.

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