Omron SYSMAC CJ1W-SCU21-V1, Operation Manual

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9
Protocol Overview Section 1-3
Slave-initiated Communications
Unit Ver. 1.2 or later supports the 1:1 Host Link protocol for C200H, C1000H,
and C2000H CPU Units, which enables the use of host programs for 1:1 Host
Links created for these PLCs. A Host Link-compatible device selection func-
tion is also provided for complete compatibility with the C-series Host Link and
CVM1/CV-series Host Link.
1-3-2 Protocol Macros
Data transfer procedures (protocols) with general-purpose external devices
are created using the CX-Protocol to match the communications specifica-
tions (half-duplex or full-duplex, and start-stop synchronization) of the external
device.
These protocols are stored in the Serial Communications Boards or the Serial
Communications Unit, and enable data to be exchanged with general-pur-
pose external devices simply by executing the PMCR(260) instruction in the
CPU Unit.
Standard system protocols for exchanging data with OMRON devices (such
as Temperature Controllers, Intelligent Signal Processors, Bar Code Readers,
and Modems) are provided as a standard feature in the Serial Communica-
tions Boards, the Serial Communications Unit, and the CX-Protocol. The CX-
Protocol can also be used to change the standard system protocols according
to user requirements.
FINS
command
Host Link
Host Link
header
Host Link
terminator
SEND(090),
RECV(098),
CMND(490) SEND(090): Sends data to host computer
RECV(098): Reads data from host computer
CMND(490): Executes any FINS command
Slave-initiated FINS commands can also
be sent from PLCs on remote networks.
FINS
command
Host Link
Host Link
header
Host Link
terminator
Remote network
(Controller Link
or Ethernet)
SEND(090),
RECV(098),
CMND(490)
FINS
command
Communications sequence
Protocol
General-purpose external device
Serial Communications Unit
PMCR(260)