Omron CJ - REFERENCE MANUAL 07-2009 User Manual

73
Serial Gateway Overview Section 3-6
3-6-5 Converting from FINS to Modbus-ASCII
Modbus-ASCII Slave-compatible devices connected serially to a PLC via
Modbus-ASCII can be accessed from the PLC using Modbus-ASCII com-
mands enclosed in FINS messages.
• Sent FINS message: FINS header + FINS command code 2805 hex +
Modbus-ASCII command
• Message after conversion: Modbus-ASCII command
System Configuration Patterns
Sending FINS Messages Using CMND(490) in CPU Unit’s Ladder Program
The Board/Unit converts the FINS messages to Modbus-ASCII protocol for
sending in this operation.
Access from CPU Unit (on the Same PLC)
Access from CPU Unit (on Network PLC)
Note (1) The FINS header contains the following information.
• Remote destination network address (DNA): Same as for CompoWay/F.
• Remote destination node address (DA1): Same as for CompoWay/F.
• Remote unit address (DA2): Same as for CompoWay/F.
(2) The contents of the Modbus-ASCII command enclosed in the FINS mes-
sage that is sent is as follows:
Slave address (ASCII) + FUNCTION code (ASCII) + Communications
data (ASCII)
2805
FINS message
FINS header Modbus-ASCII command
(Via network or CPU bus)
Modbus-ASCII command
Modbus-ASCII command
(RS-232C or RS-422A/485)
CPU Unit
(CMND(490)
instruction)
Modbus-ASCII command encapsulated
using FINS command 2805 hex
Serial Com-
munications
Unit/Board
Modbus-
ASCII Slave-
compatible
device
CPU Bus-to-Serial Details Routing tables to treat serial
communications path as network
Slaves connected serially to the Serial
Communications Board/Unit using Mod-
bus-ASCII can be accessed from a CPU
Unit in the same PLC.
Optional
2805
FINS header
CMND(490)
Modbus-ASCII command
Modbus-ASCII command
Serial Communications Unit/Board
FINS message
RS-485 (Modbus-ASCII)
CPU Unit
Protocol
conversion
Modbus-ASCII
Slave device
FINS message-to-Serial Details Routing tables to treat serial
communications path as network
Slaves connected serially to the Serial
Communications Board/Unit using Mod-
bus-ASCII can be accessed from a CPU
Unit in a PLC on the network.
Optional
2805
CMND(490)
FINS header
FINS message
Serial Communications Unit/Board
CPU Unit
RS-485 (Modbus-ASCII)
Modbus-ASCII
command
Modbus-ASCII
command
Protocol
conversion
Modbus-ASCII
Slave device
Network (Ethernet, Controller
Link, DeviceNet)

Omron CJ - REFERENCE MANUAL 07-2009 Specifications

General

Brand	Omron
Model	CJ - REFERENCE MANUAL 07-2009
Category	Computer Hardware
Language	English