Memory Regions¶

PiPLC uses word-based (32-bit) memory organized into seven regions, following traditional PLC conventions.

Region Summary¶

Region	Address Format	Data Type	Size	Description
Input	`I:word/bit`	BOOL	8 words × 32 bits	Physical inputs
Output	`O:word/bit`	BOOL	8 words × 32 bits	Physical outputs
Internal	`B:word/bit`	BOOL	64 words × 32 bits	Internal relays
Integer	`N:word`	INT32	256 words	Integer storage
Timer	`T:word`	TimerData	64 timers	Timer accumulators and status
Counter	`C:word`	CounterData	64 counters	Counter accumulators and status
Interval	`V:word`	IntervalData	Dynamic	Interval timer persistent state

Address Formats¶

Bit Addresses (I:, O:, B:)¶

Format: REGION:word/bit

I:0/0 — Input word 0, bit 0
O:1/3 — Output word 1, bit 3
B:5/15 — Internal bit word 5, bit 15

Word and bit numbers are zero-indexed. Bit range is 0–31.

Integer Addresses (N:)¶

Format: N:word

N:0 — Integer word 0
N:255 — Integer word 255

Values are 32-bit signed integers (range: −2,147,483,648 to 2,147,483,647).

Timer Addresses (T:)¶

Format: T:word or T:word.subelement

Address	Description
`T:0`	Timer 0 (full structure)
`T:0.PRE`	Preset value
`T:0.ACC`	Accumulated value
`T:0.DN`	Done bit
`T:0.TT`	Timer Timing bit
`T:0.EN`	Enable bit

Counter Addresses (C:)¶

Format: C:word or C:word.subelement

Address	Description
`C:0`	Counter 0 (full structure)
`C:0.PRE`	Preset value
`C:0.ACC`	Accumulated value
`C:0.DN`	Done bit
`C:0.OV`	Overflow bit
`C:0.UN`	Underflow bit
`C:0.CU`	Count Up enable bit
`C:0.CD`	Count Down enable bit

Interval Addresses (V:)¶

Format: V:word

V:0 — Interval 0
V:1 — Interval 1

Used by the INTERVAL instruction for persistent timing state. Tracks when the interval started, when it last triggered, and the configured period (days/hours/minutes). State survives PLC restarts.