Host Link; Nt Link - Omron Programmable Terminals NT31 NT31C Setup Manual

Communications with the Host
Features of the Direct
Connection Function

1-4-2 Host Link

1-4-3 NT Link

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The NT31/NT31C can directly write to and read from such allocated bits and
words to change the display status of the elements on the PT screen, control the
PT operating status, and notify statuses to the host.
This function, which directly reads and writes the statuses of words and bits with-
out using a PC program is called the direct connection function.
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
NT31/NT31C to be read from the memory area in the PC and written to memory
tables in the NT31/NT31C. Also, the data input at the NT31/NT31C can be writ-
ten to the memory area in the PC. The NT31/NT31C screen can be changed in
accordance with statuses in the PC memory area, and the NT31/NT31C's status
data can be written to the PC's memory area.
NT31/NT31C
The direct connection function has the following features.
• The bits and words referring to operating status and work instruction informa-
tion and those for storing input data can be freely allocated to almost any area
of the PC memory.
• Since the NT31/NT31C can directly refer to PC bit and word data without using
the program at the PC, it can be connected to the PC without changing the PC
program which controls the currently running production line.
• The area to control and notify the NT31/NT31C statuses, including display
screens, display/no display status, and buzzer output, can be freely allocated
to any part of the PC data area. This means that the PC status can be read and
controlled just by reading this area at the PC side, without preparing a special
communication program.
The direct connection function allows the NT31/NT31C to directly read and write
almost all bits and words in the PC and to automatically change the
NT31/NT31C screen display. This function can reduce the load on the PC 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 communication. This method can be
used for connection to the majority of PC types.
NT link is a method for high-speed communication with a PC using the direct
connection function. The PCs that can be connected with the NT link are as fol-
lows.
• When using the built-in host link function of a CPU unit or SRM1:
CPM1, CPM2A, CPM2C, CQM1, CQM1H, C200HS, C200HX/HG/HE(-Z)E,
CS1G/CS1H-E(V1), CVM1/CV-series PC (-EV1 or later version), SRM1
Besides the 1:1 NT Link method, in which one PC is connected to one PT, the
NT31/NT31C can also use the 1:N connection NT Link method, which allows a
maximum of eight PTs to be connected to one PC port.
PC
DM area I/O relay area
Auxiliary relay area Timers/counters
Section 1-4