Host Link Communications; Setup Area Allocations; Setup Area Words - Omron SYSMAC CS1W-SCB41-V1 Operation Manual

Host Link Communications

4-1 Host Link Communications
Host-initiated
Communications
PLC-initiated
Communications
4-2

Setup Area Allocations

4-2-1

Setup Area Words

124
Host Link System can be used to send C-mode commands or FINS com-
mands from a host computer (e.g., personal computer or PT) to a PLC to
read/write I/O memory, control operating modes, etc. The PLC can also use
the SEND(090), RECV(098), and CMND(490) instructions to send FINS com-
mands to the host computer for "slave-initiated communications." Using the
PLC to control communications enables controlling and monitoring of the
overall system operating status.
Refer to the CS/CJ-series Communications Commands Reference Manual
(W342) for details on C-mode and FINS commands.
Communications in a Host Link System are normally started by the host com-
puter.
Host computer
The host computer sends a command to the PLC. The PLC processes the
command and returns a response to the host computer. This process is
repeated, allowing the host computer to monitor and control PLC operation.
Both C-mode and FINS commands can be used in host-initiated communica-
tions.
The PLC can also initiate communications with the host computer, as may be
necessary when errors occur on the line controlled by the PLC or to confirm
the operating status of the host computer.
Host computer
The PLC sends a command to the host computer through a Serial Communi-
cations Unit or Board. The host computer processes the command and, when
necessary, returns a response to the PLC.
Using PLC-initiated communications requires that a program be prepared on
the host computer to process commands received from a PLC and return the
required responses. Only FINS commands can be used in PLC-initiated com-
munications.
Note Always transfer uppercase letters when using Host Link communications.
Lowercase letters cannot be processed.
This section describes the Setup Area allocated to the Serial Communications
Board and Serial Communications Units in the DM Area when Host Link com-
munications are used.
The Serial Communications Board and Serial Communications Units use the
following words as a Setup Area in the DM Area when Host Link communica-
tions are used. The words allocated to the Serial Communications Board are
different from those allocated to the Serial Communications Units (which are
allocated words according to the unit numbers).
Command
CS/CJ-series PLC
Response
Command
CS/CJ-series PLC
Response
Section 4-1