7 Application Instructions API 50-99 Receving data: (External equipment → PLC) Remarks: 1. PLC COM1 RS-232: Associated flags (Auxiliary relays) and special registers (Special D) for communication instructions RS / MODRD DVP-PLC APPLICATION MANUAL 7-105 D120L D121L D122L D123L D124L D125L D126L Registers for received data, starting from lower 8 bits of D120 Length = 7 D121L D122L D123L D124L D125L D126L Flag Function Action M1138 COM1 retain communication settings. Communication settings will be reset (changed) according to the content in D1036 after every scan cycle. Users can set ON M1138 if the communication protocol requires to be retained.
When M1138 = ON, communication settings will not be reset (changed) when communication instructions are being processed, even if the content in D1036 is changed. User sets and resets M1139 COM1 ASCII / RTU mode selection, ON: RTU mode, OFF: ASCII mode. User sets and resets M1312 COM1 sending request. Before executing communication instructions, users need to set M1312 to ON by trigger pulse, so that the data sending and receiving will be started. When the communication is completed, PLC will reset M1312 automatically. User sets and system resets M1313 COM1 data receiving ready. When M1313 is ON, PLC is ready for data receiving System M1314 COM1 Data receiving completed.
System sets and user resets M1315 COM1 receiving error. M1315 will be set ON when errors occur and the error code will be stored in D1250. System sets and user resets Special register Function D1036 COM1 (RS-232) communication protocol. Refer to the following table in point 4 for protocol setting. D1167 The specific end word to be detected for RS instruction to execute an interruption request (I140) on COM1 (RS-232). When the character received is equal to the low byte of D1167, the interrupt I140 is triggered. Supported communication instructions: RS D1121 COM1 (RS-232)/COM2 (RS-485) communication address when COM1/COM2 functions as a slave station.