9 Application Instructions API 150-199 DVP-PLC Application Manual 9-32 Flags Function D1129 Abnormal communication time-out. Unit: ms D1130 Records of error codes sent back from MODBUS D1256 ~ D1295 When the built-in RS-485 communication instruction MODRW is executed, the sent out data will be stored in D1256 ~ D1295. The user can check whether the instruction is correct by the contents in the registers. D1296 ~ D1311 PLC will automatically convert the ASCII data stored in the register designated by the user into hex format.