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1-1 PC Link Systems
A PC Link System is established to interconnect two or more C-series PCs
through PC Link Units to allow data transfer through the LR area of each PC.
PC Link Subsystems can be established within the PC Link System, creating
different levels of operation. Each PC in the PC Link System automatically
exchanges data with all the PCs in the same Subsystem. Any PC in two Sub-
systems (i.e., any PC to which two PC Link Units are mounted) can be used
as a “transfer PC” to transfer data between two PC Link Subsystems.
The data communications provided by PC Link Systems allow use of the in-
puts and outputs on all of the PCs in the System in the program of any PC.
PC Link Systems do not establish hierarchies of control between PCs. i.e., all
control actions must be written in the programs of individual PCs.
PC Link Systems exchange data differently to I/O Links in Optical Remote I/O
Systems in three main ways. First, an I/O Link requires the use of I/O points,
reducing the number of I/O points available to connect to I/O devices. Sec-
ond, the number of bits transferred between PCs in a PC Link System is lim-
ited only by the size of the LR area and the number of PCs in the PC Link
System; an I/O Link in a Remote Optical System can handle only one or two
words. Third, I/O Links use programmed input and output operations to trans-
fer data, whereas PC Link Systems use an automatic polling method.
PC Link Systems access only the LR area of the PC for data exchange and
do not require the use of any of the PCs I/O points.
Settings on the PC Link Units allow for data exchange little or no program-
ming required.
Two PC Link Subsystems operating at different levels can exchange data via
the LR area of a PC operating in both Subsystems.
The C500-LK009-V1 differs from the 3G2A5-LK009 in insulation of the trans-
mission section from the internal circuits to improve anti-noise performance.
This increased performance reduces noise interfere originating in ground dif-
ferences, cable inductance, etc. The C500-LK009-V1 can also be used to-
gether with the C200H-LK401. This is not possible with the 3G2A5-LK009.
Although not covered in detail in this manual, the LK003-E PC Link Unit can
be used in PC Link Systems together with the LK009-V1 PC Link Unit. If the
LK003-E is used, the PC Link System must be single-level and all LK009-V1
PC Link Units in the System must be set to LK003-E mode. The LK003-E (or
an LK009-V1 in LK003-E mode) can be used only on C500 PCs and cannot
be used in the same PC Link System as a C200H-LK401 PC Link Unit.
1-2 Operating Levels and Polling
All PC Link Units are assigned unit numbers which determine what part of
the LR area each is to be allocated. Whenever two or more PCs are con-
nected in a PC Link System, one of the PC Link Units must be set as the poll-
ing unit (i.e., as Unit #0) and all other PC Link Units must be set as polled
units (i.e., as any Unit other than #0). The polling unit of each PC Link Sub-
system does not control the other PCs, which are each controlled independ-
ently by their own CPUs.
Compared with I/O Links
Effective I/O Utilization
Simplified System Setup
Subsystem Data Exchange
LK009-V1 Improvements
LK003-E PC Link Units
Operating Levels and Polling Section 1-2