Modbus Tcp Client - IDEC SmartAXIS FT9Z-1A01 User Manual

Modbus TCP Client

When configured as a Modbus TCP client, the SmartAXIS 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 SmartAXIS 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
*1: Specifies the period of time before receiving a response frame from a server.
Modbus TCP Client Start and Stop
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. The internal relays or data register bits
are allocated in the order of requests. 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.
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.
Use a single DR for all
communication requests
Unchecked
Checked
Bit Allocation
Remote Host Number
(high-order byte)
Error Code
(low-order byte)
Parameter
Error data, the remote host number (high-order byte) and error code (low-order byte), of each request in the
entire request table can be confirmed. Data registers as many as the quantity of requests are reserved for
storing error data. When an error occurs for a request, error data is stored to the corresponding data register.
A single data register is shared by all requests. When an error occurs for a request, error data is stored to the
data register and the old error data is overwritten.
1 to 255
00h: Normal completion
01h: Function code error (unsupported function code)
02h: Access destination error (address out of range, address+device quantity out of range)
03h: Device quantity error, 1-bit write data error (specified device quantity of 1-bit write is unsupported)
12h: Frame length error (frame length of transmitted request exceeds range)
13h: BCC error (BCC does not match)
14h: Slave number error (received slave number is invalid)
16h: Timeout error (timeout occurs)
S A XI S P
M AR T R O
1 to 247
3 (one server per one connection)
100 to 25,500ms (in increments of 100ms)
Error data of each communication request
/ L U ' M FT9Y-B 1378
I TE SER S ANUAL
11: M C
ODBUS OM M UN I CATI ON
Modbus TCP Client
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