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8-2 Host Link Communications
8-2-1 Host Link Command Summary
Host Link communications are used to transfer data between the PC and a host
computer (a personal computer or PT). It is possible to monitor the PC’s operat-
ing status and the contents of PC data areas from the host computer using Host
Link commands. It is also possible to transfer data from the PC’s IOM data areas
(IR area, SR area, LR area, HR area, AR area, timer and counter PVs, DM 0000
through DM 6143, and EM 0000 through EM 6143) to a host computer using the
TXD(––) instruction in the ladder program.
RS-232C Connections (1-to-1) Only one PC can be connected with the host computer (one-to-one connection)
when the Host Link is made with RS-232C connections.
Host Link
Host Link
Host
computer
Host
link
IBM PC/AT or compatible
Up to 32 PCs can be connected with the host computer (one-to-N connection)
when the Host Link is made with RS-422/485 connections.
Host link
32 PCs max.
IBM PC/AT or compatible
See
note
Note: RS-232C ↔ RS-422/485 Adapter
See
note
See
note
See
note
Wiring Ports Use the wiring diagram shown below as a guide in wiring the port to the external
device. Refer to documentation provided with the computer or other external de-
vice for wire details for it.
RS-422/485 Connections
(1-to-N)
Host Link Communications
Section 8-2