There are 3 different types of memory cards available for Q-Series PLCs and it is important to choose the correct one as they do not all support the same features. The 3 types are SRAM (RAM), Flash (ROM) and ATA (ROM).
It is important to remember that adding ANY memory card to a Q-Series PLC will NOT expand the program memory. If your PLC supports 14K program steps then that is all you are going to get. Memory cards in a Q-Series PLC system can be used to gain things like more file registers or somewhere to put IEC programming symbolic information, as detailed below.
- Program backup means that the PLC program can be stored in ROM and loaded into RAM on the PLC startup but ultimately it still runs in the normal program RAM.
- File registers (R registers) are 16-bit words, thus for a 4MB memory card the maximum possible number of file registers is 2 M words (1 word = 2 bytes).