Campbell CR800 Series - Read Only Variables; Signatures; Memory

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Section 8. Operation

406

being copied, or making it tamper resistant. .CR<X> files, or files specified by

the Include() instruction, can be hidden using the FileHide() instruction. The

CR800 can locate and use hidden files on the fly, but a listing of the file or the file

name are not available for viewing. See File Management in CR800 Memory

(p.

416).

8.7.7 Signatures

Recording and monitoring system and program signatures are important

components of a security scheme. Read more about use of signatures in

Programming to Use Signatures

(p. 169) and Signatures: Example Programs (p. 180).

8.7.8 Read Only Variables

The following example of variable declaration demonstrates how to display a

value in numeric display (Connect or RTMC) or on a CR1000KD but not allow

the person viewing it to make changes:

• Var can be viewed and changed

• Reg() and Coil() can only be viewed

• The CRBasic program can read from and write to all variables

Public Var

Public Reg(4), Coil(4) as Boolean

ReadOnly Reg, Coil

8.8 Memory — Details

Campbell CR800 Series - Read Only Variables; Signatures; Memory - Details; Storage Media