Modbus Tcp Client - IDEC FC6A-C16K1CE Communications Manual

Modbus TCP Client

When configured as a Modbus TCP client, the FC6A Series MicroSmart sends communication requests to a Modbus TCP server to
read/write data. Each communication request is sent to a Modbus Server according to the configured request table.
Modbus TCP client communication settings and request tables for Modbus TCP servers can be configured using the WindLDR
Function Area Settings. The FC6A Series MicroSmart communicate with the Modbus TCP servers according to those settings.
Communication with Modbus TCP servers are performed in sync with the user program execution, and the communication data is
processed at the END, in the order of request numbers specified in the request table.
Modbus TCP Client Specifications
Slave Number
Maximum Number of Servers
*1
Receive Timeout
Transmission wait time
*1 Specifies the period of time before receiving a response frame from a server.
Request Execution
Device
Used
Unused
Auto ping linking
The FC6A Series MicroSmart operation when combining the request execution setting is as follows.
Request Execution Setting
Do not use
Request execution
device
Use
Communication Completion and Communication Error
Modbus communication finishes when a read or write process is completed successfully or when a communication error occurs.
A communication error occurs when communication failure has repeated three times. When a communication error occurs, the
request is canceled and the next request is processed. When the error status data register is designated, the communication status
of each request can be confirmed.
Communication Error Data
When Error Status is configured in the Request Table from the Function Area Settings, the error data of each request can be
confirmed.
Parameter
When request execution devices are designated in the Modbus TCP Client request table, internal relays
or data register bits (as many as the request quantity) are allocated to execute Modbus TCP Client
communication. For example, when internal relay M0 is designated as the request execution device, M0
is allocated to request No. 1, M1 to request No. 2, and so on. To execute a request, turn on the
corresponding request execution device.
When communication is completed, the request execution device turns off automatically. When it is
required to send requests continuously, keep the corresponding request execution device on using a SET
or OUT instruction.
When request execution devices are not designated, all requests programmed in the request table are
executed continuously.
The internal relays or data register bits are allocated in the order of requests.
Whether or not to send a request from the Modbus TCP client can be controlled with online status on/off via auto ping
linking. This eliminates unnecessary timeouts by not sending requests to remote hosts that are not part of the network.
For details on auto ping linking, see "Auto Ping Function" on page 3-18.
Always send all requests.
Send the applicable request only when the
communication execution device is on, and when
it is off, do not send the applicable request.
FC6A S M S A
ERIES ICRO MART
1 to 247
8 (one server per one connection)
100 to 25,500 ms (in increments of 100 ms)
0 to 5,000 ms (0 ms)
Start/stop
Auto Ping Linking
Do Not Use
- -O T C
LL IN NE YPE OMMUNICATION
6: M
ODBUS
Modbus TCP Client
Use
Send the applicable request only when the online
status is on, and when it is off, do not send the
applicable request.
Send the applicable request only when the online
status and the communication execution device
are both on, and do not send the applicable
request in all other cases.
M FC9Y-B1730
ANUAL
C
OMMUNICATION
6-19