Appendix A: System Data Types; Table 6: System Bit Functions - Unitronics Vision 120 OPLC User Manual

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 Bits (SB)
0
1
2
3
4
5
6
7
8
30
31*
32
40-63
200*-215*
236
237*
250
251
System Bit Functions
Function
Always 0
Always 1
Power-up bit
1 second pulse
Divide by zero
Output(s) short circuit
Keyboard is active
100 mS pulse
Battery low
HMI keypad entries completed
Refresh current LCD screen display
HMI keypad entry in progress
Keypad keys (see the following table)
Network operands
Network communication error
Network disable
Keypad entry within limits
Keypad entry exceeds limits
33