Modbus slave (RTU) This section contains information on the following topics:Modbus instructions (S7-300, S7-400)MODB_341: Modbus slave instruction for CP 341 (S7-300, S7-400)MODB_441: Modbus slave instruction for CP 441 (S7-300, S7-400)ERROR_NR, ERROR_INFO parameters (S7-300, S7-400)SYSTAT error message area (S7-300, S7-400)