Converting From Fins To Modbus-Ascii - Omron SYSMAC CS1W-SCB41-V1 Operation Manual

Protocol Conversion
6-5-5

Converting from FINS to Modbus-ASCII

System Configuration Patterns
Sending FINS Messages Using CMND(490) in CPU Unit's Ladder Program
CPU Bus-to-Serial
Serial Communications Unit/Board
CPU Unit
Protocol
FINS header
conversion
Modbus-ASCII command
Modbus-ASCII
Slave device
FINS message-to-Serial
FINS header
Serial Communications Unit/Board
CPU Unit
Protocol
conversion
Modbus-ASCII
command
Modbus-ASCII
Slave device
220
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
FINS message
CPU Unit
(CMND(490)
FINS header
instruction)
Modbus-ASCII command encapsulated
using FINS command 2805 hex
(Via network or CPU bus)
The Board/Unit converts the FINS messages to Modbus-ASCII protocol for
sending in this operation.
Access from CPU Unit (on the Same PLC)
CMND(490)
FINS message
2805
Modbus-ASCII command
RS-485 (Modbus-ASCII)
Access from CPU Unit (on Network PLC)
CMND(490)
FINS message
Modbus-ASCII
2805
command
Network (Ethernet, Controller
Link, DeviceNet)
RS-485 (Modbus-ASCII)
Serial Com-
2805
Modbus-ASCII command
munications
Unit/Board
Details
Slaves connected serially to the Serial
Communications Board/Unit using Mod-
bus-ASCII can be accessed from a CPU
Unit in the same PLC.
Details
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.
Section 6-5
Modbus-ASCII command
Modbus-
ASCII Slave-
Modbus-ASCII command
compatible
device
(RS-232C or RS-422A/485)
Routing tables to
treat serial
communications
path as network
Optional
Routing tables to
treat serial
communications
path as network
Optional