ICP DAS, MDC-211-WF user manual , v1.1 Page
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5.
FAQ
Q1 - What are the maximum numbers of polling definition and Internal
Register in a MDC-211-WF?
The maximum number of polling definition in a MDC-211-WF is 240 commands, each
definition can access up to 64 Internal Registers. Each of the four tables (DI/DO/AI/DO) can
store up to 9600 Internal Registers for polled data.
Q2 - What is the maximum number of data can be accessed in one
command from a Modbus Master device?
By the Modbus TCP protocol, the maximum amount of Internal Registers that one Modbus
command can access is 255 of function code 01 and 02, and 126 of function code 03 and 04.
Q3 - How are the Internal Registers corresponding to the polled data in a
MDC-211-WF?
Please refer to the "2.6.2 Inquire Corresponding Modbus Register Address" for the detail
information.
Q4 - How to read each MDC-211-WF command status via the Modbus
communication?
MDC-211-WF can view the real-time status of each Modbus command directly in a
Web UI, and also store the status in the Internal Register starting with the address 39600
(0x2580), that meaning the Modbus Master can use function code 04 to read the command
status. One command can read up to 126 Internal Register data.