User guide

Hardware
16
890 USE 108 00 August 2001
Memory User memory is the amount of memory available for your user logic program (one
word comprises 16 bits).
State RAM memory is used to hold register and discrete inputs and outputs and
internal data storage. State RAM is allocated to the four different reference types
(0xxxx, 1xxxx, 3xxxx, and 4xxxx). (See System Capacity, p. 18).
Memory Partition Option with Concept 2.1. When using the E984-258/265/275/
285 PLC with Concept 2.1 or higher you may partition the total SRAM memory.
The five IEC languages in Concept share the same memory space as the 984LL
language and 16-bit Loadables. When you enable the IEC usable memory size
in Concept, you allocate a specific amount of memory to IEC thus limiting the
amount of memory for 984LL and loadables
This is the Allocation Table.
The following is an example using a E984-275 requiring: Modbus master (XMIT
Loadable), an AGA gas flow (GD2 Loadable), 984LL memory of 3K words, and IEC
Structured Text (ST) program of 20K bytes.
PLC Model SRAM Size IEC Minimum Memory Size IEC Maximum Memory Size
-258/265/275 512K 68 k bytes 220 k bytes
-285 1 Meg 68 k bytes 620 k bytes
Note: Concept language memory is measured in k bytes (8 bits). In contrast,
984LL language memory is measured in K words.