CPM1A - memory backed up

[pszczepan 2]

Hi ! I will make an application which also store recipes in DM memory. I read about internal capacitor which can backed up DM memory up to 20 days. Is there any other internal supplier (battery.) which can backed up data in DM memory longer then 20 days. Pawel

[Nibroc 4]

Hello, No - the CPM1A will retain the DM memory for only 20 (+/-) days.!! Use a CPM2A which has a battery to retain the data for longer (5+ years). Alternately, if your recipe data is not large, you could use multiple MOV instructions in your program to 'preset' the data. (the ladder program is retained permanently) Nibroc

[pszczepan 2]

Hello ! Could you be more specific about using MOV to save recipes in my ladder program. My idea is writing recipe parameters via NT panel and I want to use indirect addressing to put them in DM memory. How I can transfer it to permament memory as you said. Thanks Pawel

[ilsk8 0]

Depending on what editor you are using? CX-Programmer or Syswin, they both have DM, Timer, Counter, I/O editors as well as the ladder editor so that the values and settings can be saved for multiple programs. I learnt the hard way by losing DM and Timer values by not saving the DM as well as the Ladder every time I would try a new program to experiment on my own CPM1A. As far as the MOVE function, that’s all it dose is move DM values around the DM area and is still governed by the supper capacitor 20 day or more memory.

[PdL 71]

Nibrocs suggestion is also useful for default setpoint functionality. In most installations with user changaeble setpoints, we put all tyhe default values as fixed numbers in MOV instructions, which all can be triggered by a "load default setpoint" button somewhere in the HMI. Especially usefull if the customer has screwed up the installation by changing setpoints and not knowing what the initial setting was. If they call with a problem, we always ask to first load the default settings. In most cases the problem is gone after having the settings as they were commissioned, if not you are sure the problem isn't caused by a faulty setpoint. Edited 3 Mar 2005 by PdL

[Nibroc 4]

Hello pszczepan, Your idea of using the HMI and indirect addressing to store/edit/retrieve recipe data is good. (this is quite a common technique) You will not be able to store this data permanently in a CPM1a (unless the power is always on), as your data will not be constant (ie the operators can change it via the HMI). Using the MOV function to set constants from the ladder program will not work for dynamic (changing) data. This technique is only used to preload memory addresses with constant values (not changeable ones). It can be handy as PdL mentioned to reset defaults, or set constant data via the ladder program. If your PLC is disconnected for more than 20 days as part of its normal operation, you will need a PLC with retentative data area's such as a CPM2a which has a battery allowing 5+ years of backup. Nibroc