adccommunitymod (AutomationDirect) asked a question.
Created Date: February 09,2012
Created By: scott.lawrence
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I'm puzzled by this. Randomly, the plc 'loses ' memory in the retentive memory. I'm using V1500 - V4777 to store position data from HMI for different parts being processed. Today, when the operator powered up the machine & went to a part run page on the HMI, all fields were empty. After scrolling through the rest of the run pages, none had the previously input data, but instead showed zeros (the positions are entered numerically). This has happened three times since the machine was put in operation, roughly September 2011. Further info, the V registers are only used to store the data. There is nothing overwriting or erasing the data from a program standpoint. The plc does have a battery, and the retentive ranges are from V400-37777. I searched the first two pages of the forum, but didn't find any info, so....any ideas?
Created Date: February 09,2012
Created by: Bob S BN
Did you set bit 12 of V7633?
An excerpt from page 3-11 of D2 user manual volume 1...
In the DL205 CPUs, the battery can be enabled by setting bit 12 in V7633 On. In this
mode the battery Low LED will come on when the battery voltage is less than
2.5VDC (SP43) and error E41 will occur. In this mode the CPU will maintain the data
in C,S,T,CT, and V memory when power is removed from the CPU, provided the
battery is good. The use of a battery can also determine which operating mode is
entered when the system power is connected. See CPU Setup, which is discussed
later in this chapter.
Created Date: February 09,2012
Created by: Do-more PE
As Bob said, check the battery and setup first. If it is good then it is probably caused by a power event of some sort.
The loss of memory with a power event is quite rare, but a lightning strike or other large spike on the power or communications line can possibly cause the volatile memory to erase. If you do not have any surge suppression on the incoming PLC power you might want to consider installing some.
If you have communications lines that run more than 20 feet or so you might want to consider getting isolation devices to keep any unwanted spikes from coming into the PLC from that route as well.
Created Date: February 09,2012
Created by: scott.lawrence
Bob & ADC : B7633.12 is being 'set ' on first scan, with no reset in the program. The battery low indicator wasn't on, and there was no error from the CPU. The PLC went into Run mode on power-up, as expected, it was just missing the data between V1500 & V6000 (Data Collection Storage).
Created Date: February 09,2012
Created by: scott.lawrence
I'm puzzled by this. Randomly, the plc 'loses ' memory in the retentive memory. I'm using V1500 - V4777 to store position data from HMI for different parts being processed. Today, when the operator powered up the machine & went to a part run page on the HMI, all fields were empty. After scrolling through the rest of the run pages, none had the previously input data, but instead showed zeros (the positions are entered numerically). This has happened three times since the machine was put in operation, roughly September 2011.
Further info, the V registers are only used to store the data. There is nothing overwriting or erasing the data from a program standpoint. The plc does have a battery, and the retentive ranges are from V400-37777.
I searched the first two pages of the forum, but didn't find any info, so....any ideas?