GE 90-30/20/Micro manual System Status References, Reference Nickname Definition

2

System Status References

System status references in the Series 90 PLC are assigned to %S, %SA, %SB, and %SC memory. They each have a nickname. Examples of time tick references include T_10MS, T_100MS, T_SEC, and T_MIN. Examples of convenience references include FST_SCN, ALW_ON, and ALW_OFF.

Note

%S bits are read-only bits; do not write to these bits. You may, however, write to %SA, %SB, and %SC bits.

Listed below are available system status references, which may be used in an application program. When entering logic, either the reference or the nickname can be used. Refer to chapter 3, “Fault Explanations and Correction,” for more detailed fault descriptions and information on correcting the fault.

You cannot use these special names in another context.

Table 2-6. System Status References

Reference	Nickname	Definition
%S0001	FST_SCN	Set to 1 when the current sweep is the first sweep.
%S0002	LST_SCN	Reset from 1 to 0 when the current sweep is the last sweep.
%S0003	T_10MS	0.01 second timer contact.
%S0004	T_100MS	0.1 second timer contact.
%S0005	T_SEC	1.0 second timer contact.
%S0006	T_MIN	1.0 minute timer contact.
%S0007	ALW_ON	Always ON.
%S0008	ALW_OFF	Always OFF.
%S0009	SY_FULL	Set when the PLC fault table fills up. Cleared when an entry is
		removed from the PLC fault table and when the PLC fault table is cleared.
%S0010	IO_FULL	Set when the I/O fault table fills up. Cleared when an entry is
		removed from the I/O fault table and when the I/O fault table is cleared.
%S0011	OVR_PRE	Set when an override exists in %I, %Q, %M, or %G memory.
%S0013	PRG_CHK	Set when background program check is active.
%S0014	PLC_BAT	Set to indicate a bad battery in a Release 4 or later CPU. The
		contact reference is updated once per sweep.

2-24 Series 90-30/20/Micro Programmable Controllers Reference Manual– September 1998 GFK-0467K