GE 90-30/20/Micro Function Block Structure

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

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.

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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