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Rockwell Automation Publication 2080-UM002L-EN-E - November 2021
Appendix B Modbus Mapping for Micro800
Performance
The performance of MSG_MODBUS (Micro800 is master) is affected by the
Program Scan because messages are serviced when the message instruction is
executed in a program. For example, if the program scan is 100 ms and six
serial ports are used, then the theoretical maximum for serial ports is 60
messages/second total. This theoretical maximum may not be possible since
MSG_MODBUS is a master/slave request/response protocol, so performance is
affected by several variables such as message size, baud rate, and slave
response time.
The performance of Micro800 when receiving Modbus request messages
(Micro800 is slave) is also affected by the Program Scan. Each serial port is
serviced only once per program scan.