Unitronics Vision 120 OPLC, User Manual

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Appendix A: System Data Types
The Vision OPLC operating system – user program interface includes System Bits (SB),
System Integers (SI), System Long Integers (SL), and System Double Words (SDW) listed in
the tables below. Specific data types are linked to fixed parameters and are read-only by the
user program, such as
SB 2 Power-up bit .
You may write into certain data types. These are marked with an asterisk (*), such as
SI 8 Unit ID . All SBs, SIs, SLs, and SDWs not listed are reserved for use by the system.
To obtain a complete, updated list of system operands, refer to the VisiLogic software.
Table 6: System Bit Functions
System Bits (SB) Function
0 Always 0
1 Always 1
2 Power-up bit
3 1 second pulse
4 Divide by zero
5 Output(s) short circuit
6 Keyboard is active
7 100 mS pulse
8 Battery low
30 HMI keypad entries completed
31* Refresh current LCD screen display
32 HMI keypad entry in progress
40-63 Keypad keys (see the following table)
200*-215* Network operands
236 Network communication error
237* Network disable
250 Keypad entry within limits
251 Keypad entry exceeds limits