Campbell CR800 Series, Operator'S Manual

Page: 406 / 598

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
Related Topics:
•
Memory — Overview
(p. 89)
• Memory — Details
(p. 406)
• Data Storage Devices — List
(p. 571)
•
TABLE: Info Tables and Settings: Memory
(p. 535)
8.8.1 Storage Media
CR800 memory consists of four non-volatile storage media:
•
Internal battery-backed SRAM
•
Internal flash
• Internal serial flash
•
External flash (optional flash USB: drive)