IDEC MicroSmart Pentra - Manual (Page 93)

W EB S ERVER CPU M ODULE U SER ’ S M ANUAL FC9Y-B1278 9-5
9: M ODBUS TCP C OMMUNICATION
Master Device Address
When function code 01, 02, 03, or 04 is selected to read data from Modbus servers, designate the first data register or
internal relay number to store the data received from the Modbus server. When function code 05, 06, 15, or 16 is
selected to write data to Modbus servers, designate the first data register or internal relay number to store the data to
write to the Modbus server. Data registers and internal relays can be designated as the master device address.
Data Size and Word/Bit
Designate the quantity of data to read or write. The valid data size depends on the function code. When function code
01, 02, 05, or 15 is selected, designate the data size in bits. When function code 03, 04, 06, or 16 is selected, designate
the data size in words. For valid data sizes, see “Function Code” on page 9-4.
Remote Host No.
Designate the remote host number configured in the Remote Host List dialog box. In the Remote Host List dialog box, IP
address/host name and port number are configured for each remote host. The default port number of Modbus TCP
communication is 502. If the Modbus TCP server uses different port number, configure that port number in the Remote
Host List dialog box.
Slave No.
Designate slave numbers 1 through 247. The same slave number can be designated repeatedly for different request
numbers which can be 1 through 255. The slave number is usually not referred by Modbus TCP server. Configure the
slave number if Modbus TCP server requires.
Slave Address
Designate data memory addresses of Modbus servers. The valid slave address range depends on the function code. For
valid slave addresses, see the table above.
Request Execution Device
To use request execution devices, click the radio button for “Use” and designate the first internal relay number in the
Modbus TCP Client Request Table. Internal relays used for executing requests are automatically listed in the table. To
execute a request, turn on the corresponding request execution device.
When request execution devices are not designated, all requests programmed in the Request Table are executed
continuously.
Error Status Data Register
To use error status data registers, click the radio button for “Use” and designate the first data register number in the
Modbus TCP Client Request Table. Data registers used for storing error statuses are automatically listed in the table.
When Use a single DR for all communication requests is selected, the first data register is shared by all requests.