AH500 Hardware and Operation Manual 
11-72 
11.3.2.4  Modbus TCP Data Exchange – Special Auxiliary Relays 
 
SM700 
↓ 
Enable the execution of data 
exchange through Modbus TCP 
R/W 
ON: Enable the execution of data exchange 
through Modbus TCP connection 1~128 
SM828 
↓ 
Error flag of data exchange 
through Modbus TCP connection 
R/W 
ON: Error flag of data exchange through Modbus 
TCP connection 1~128 
SM1089 
The connection quantity of 
Modbus TCP Server has reached 
R 
ON: The connection quantity of Modbus TCP 
Server has reached its maximum.