GE 90-30/20/Micro manual Function Block Structure

2

Table 2-6. System Status References - Continued

Reference	Nickname	Definition
%SB0010	BAD_RAM	Set when the CPU detects corrupted RAM memory at power-up.
		Cleared when the CPU detects that RAM memory is valid at power-up.
%SB0011	BAD_PWD	Set when a password access violation occurs. Cleared when the PLC
		fault table is cleared.
%SB0013	SFT_CPU	Set when the CPU detects an unrecoverable error in the software.
		Cleared by clearing the PLC fault table.
%SB0014	STOR_ER	Set when an error occurs during a programmer store operation. Cleared
		when a store operation is completed successfully.
%SC0009	ANY_FLT	Set when any fault occurs. Cleared when both fault tables have no
		entries.
%SC0010	SY_FLT	Set when any fault occurs that causes an entry to be placed in the PLC
		fault table. Cleared when the PLC fault table has no entries.
%SC0011	IO_FLT	Set when any fault occurs that causes an entry to be placed in the I/O
		fault table. Cleared when the I/O fault table has no entries.
%SC0012	SY_PRES	Set as long as there is at least one entry in the PLC fault table. Cleared
		when the PLC fault table has no entries.
%SC0013	IO_PRES	Set as long as there is at least one entry in the I/O fault table. Cleared
		when the I/O fault table has no entries.
%SC0014	HRD_FLT	Set when a hardware fault occurs. Cleared when both fault tables have
		no entries.
%SC0015	SFT_FLT	Set when a software fault occurs. Cleared when both fault tables have
		no entries.

Note: Any %S reference not listed here is reserved and not to be used in program logic.

Function Block Structure

Each rung of logic is composed of one or more programming instructions. These may be simple relays or more complex functions.

Format of Ladder Logic Relays

The programming software includes several types of relay functions. These functions provide basic flow and control of logic in the program. Examples include a normally open relay contact and a negated coil. Each of these relay contacts and coils has one input and one output. Together, they provide logic flow through the contact or coil.

Each relay contact or coil must be given a reference which is entered when selecting the relay. For a contact, the reference represents a location in memory that determines the flow of power into the contact. In the following example, if reference %I0122 is ON, power will flow through this relay contact.

%I0122

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2-26 Series 90-30/20/Micro Programmable Controllers Reference Manual– September 1998 GFK-0467K