AH500 Programming Manual 8. If the communication timeout occurs, SM104 and SM105 are ON, and SM98 and SM99 are OFF. 9. If the error occurs during the reception of the data, SM102 and SM103 are ON, and SM98 and SM99 are OFF. 10. If the function code specified by S 2 is related to the word device, the device in the external equipment with which the AH500 series PLC communicates has to be the word device. If the function code specified by S 2 is related to the bit device, the device in the external equipment with which the AH500 series PLC communicates has to be the bit device. 11. The flags related to the instruction MODRW:
Please refer to the explanation of the instruction RS for more information about the functions of the flags. 6-422 Flag Description COM1 COM2 SM96 SM97 The data is sent through COM1/COM2. SM98 SM99 Waiting to receive the reply through COM1/COM2 SM100 SM101 Reception through COM1/COM2 is complete. SM102 SM103 An error occurs during the reception of the data through COM1/COM2 SM104 SM105 No data is received through COM1/COM2 after a specified period of time. SM209 SM211 The communication protocol of COM1 changes (in accordance with SM210, SR201, SR209, and SR215).