Mitsubishi A1SJH, R and D Registers

[tabrez]

Hi Everybody
Can anybody tell me what is the difference between R(File Registers) and D(Data Registers)
even i go through the programming manual of A1SJH PLC
i did not get clear picture of it.

 

[Potter]

R (File registers) retain there value when the PLC is turned off.
D (data registers) do not, there value is zero when the PLC is turned back on.

 

[Andybr]

Potter did not mention that R registers are not present by default. You need to set these up in the system parameters if you wish to use them.

 

[Unregistered]

Colt

You should also note that File registers exist in user memory space (hence the need to set them up in Parameters and their retention capability) and so by using them the overall user memory available to you is decreased. A similar performance can be realised using the D registers by assigning them retention (battery backup) characteristics in PLC Parameters - Devices (GX Developer).