Chapter 2 Devices 2_ 2.2.16 Additional Remarks on Special Auxiliary Relays and Special Data Registers 1. Scan timeout timer SM8/SR8 When a scan timeout occurs during the execution of the program, the error LED on the PLC changes to continuous ON, and SM8 changes to ON. 2. Clearing the warning light SR8 contains the step address at which the watchdog timer changed to ON. SM22 Setting SM22 to ON clears the error log and the warning light. 3. The real-time clock SM220, SR220–SR226, and SR391–SR397 SM220: Calibrate the real-time clock within ±30 seconds When SM220 changes from OFF to ON, the system calibrates the real-time clock.
If the second value in the real-time clock is in the range 0–29, the minutes value is fixed, and the seconds value 2-107 Special data Time to refresh register SR1000–SR1006 1. Register is refreshed by you. 2. Register is refreshed after power-on or after HWCONFIG is downloaded. SR1007 Register is refreshed by the system. SR1009 Register is refreshed by the system. SR1010 Register is refreshed by you. SR1011–SR1014 Register is refreshed by the system. SR1015 Register is refreshed by you. SR1020–SR1107 1. Refresh the register when a connection is established. 2. Refresh the register every scan cycle. SR1116–SR1117 Refresh the register when the program is downloaded to the PLC.
SR1120–SR1183 Refresh the register when the communication is complete. SR1312-SR1315 Refresh the register during communication Refresh the register when the parameter is downloaded to the PLC, or when the PLC is supplied with power. SR1318–SR1320 SR1335–SR1336 Refresh the register every scan cycle after the function of data exchange is enabled. SR1340–SR1371 Refresh the register when there is an error. SR1375–SR1376 Refresh the register every scan cycle after the function of data exchange is enabled. SR1380–SR1411 Refresh the register when there is an error.
SR1435–SR1436 Refresh the register during communication SR1440–SR1471 Refresh the register when error occurs during communication SR1475–SR1476 Refresh the register during communication SR1480–SR1511 Refresh the register when error occurs during communication SR1520–SR1535 Refresh the register after the communidation through AS-FEN02 is complete. SR1536–SR1540 Register is refreshed by the system. SR1559–SR1592 Register is refreshed by the system when when the system is supplied with power, disconnect from the remote module or reestablish the remote module connection.