Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved.
∗
E-mail: [email protected] - 44 -
6.2. Configuring polling definition
Before start to configure the parameters for the Polling Definition, be sure to check the COM port number
that the target device is connected to, the Modbus ID for every Modbus RTU device, function code, start
address, and the quantity for reading data. Up to 250 Modbus RTU commands can be performed in a
MDCL-700 module, and up to 9600 registers for each of AI, AO, DI, and DO type data can be used.
Each Polling Definition consists of 10 parameters listed as below:
Item
Description
#
Defines the type for a polling definition:
“
*
”: Asterisk symbol denotes a valid polling definition. The MDCL will assign local
register for data defined in the definition and put the polled data to the register.
“
-
”: Minus sign denotes a disabled polling definition. The MDCL will assign local
register for data defined in the definition but
not
poll data. It can be applied
where one or more devices are not used in different scenarios, but reserving the
mapped register addresses is helpful for the management and maintenance of
different projects.
“ ”: A blank value in this field denotes a null polling definition. The MDCL will neither
assign local register for data defined in the definition nor poll data. It is suitable
for recording previously used commands.
UseComPort
Defines the COM port number to which the slave device is connected. The COM port
number is from 1 to the total number of COM ports on the MDCL.
SlaveModbusID
Defines the identification of the remote slave. The valid range is from 1 to 255.
FunctionCode
Defines the request function code. A valid code can be 1 (Read DO), 2 (Read DI), 3
(Read AO) or 4 (Read AI) depending on the I/O features of the slave device.
RegStartAddr
Defines the starting address, i.e. the address of the first register specified.
The available range is from 0 to 65535
.
