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Toolbox 32 User Manual 1.47d www.cse-semaphore.com/mykingfisher

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Indirect Addressing

When addressing a register, the register number is usually hardcoded in the address eg. #R1. The register

number can also be specified indirectly by putting the register number in another register (the pointer

(eg. 0 or 3000), the indirect register address will return an incorrect value. Indirect addressing is extremely

useful for reducing the amount of ladder logic required to perform a repetitious task (eg. calculating the

average rainfall per minute for the last 60 minutes).

Indirect Address

Description

Example

#R[Rx]

#F[Rx]

#L[Rx]

Indirect local, float or long

#R1 = 2

#R2 = 1000

#R[R1] = #R2 = 1000

#Rx.[Ra*] Indirect local bit. Local

to a bit of register Rx

#R1 = 16

#R2.16 = 1 = ON

#R2.[R1] = #R2.16 = 1 (ON)

#R[Rx].[Ra*] Indirect local register and

bit

#R1 = 3

#R2 = 16

#R3 = 8000 Hex (Bit 16 ON)

#R[R1].[R2] = #R3.16 = 1 (ON)

#NR[Ra*].n

(n=1 to 2048)

Indirect network RTU #R1 = 2

#NR2.1 = 1000

#NR[R1].1 = #NR2.1 = 1000

#NR[Ra*].[Rx] Indirect network RTU and

#R1 = 2

#R2 = 5

#NR2.5 = 1000

#NR[R1].[R2] = #NR2.5 = 1000

#NR[Ra*].[Rx].[Rb*] Indirect network RTU,

#R1 = 2

#R2 = 1

#R3 = 16

#NR2.1.16 = 1 = ON

#NR[R1].[R2].[R3] = #NR2.1.16 = 1 = ON

#R[Rx+nnn]

or #R[Rx-nnn]

(nnn = -128 to +127)

Indirect local register with

offset. nnn is an offset that

is added or subtracted to

the pointer register Rx

Useful when a block of local registers is used to store a

number of values. One register would be used as a

pointer to the first register in the array, then any of the

other registers in the array could be accessed from the

same pointer register

* Ra, Rb and Rc must be in the range of R1 to R256 due to memory limitations of indirect addressing.

Rx can be any local register (R1 to R2048)

Examples

Please see the topics Example - Indirect Addressing or Example - Time Based Rolling Averages.