Introduction

Blocking conditions caused during the execution of the application program do not cause system errors, but they stop the CPU. The CPU goes into the HALT state.

NOTE:

  • When a BMEH58•040 CPU is in the HALT state, the RIO and DIO outputs behave the same way as they do when the CPU is in STOP state.

  • For information about Hot Standby diagnostics, refer to the diagnostics chapter in the M580 Hot Standby installation guide.

Diagnostics

Visual indications of a blocking condition are the ERR LED on the CPU front panel.

A description of the error is provided in system word %SW125.

The address of the instruction that was executing when the blocking condition occurred is provided by system words %SW126 through %SW127.

%SW125 system word values and corresponding blocking condition description:

%SW125 Value (hex)

Blocking Condition Description

0•••

execution of an unknown function

0002

SD card signature feature (used with SIG_CHECK and SIG_WRITE functions)

2258

execution of the HALT instruction

2259

execution flow different than the reference flow

23••

execution of a CALL function towards an undefined subroutine

81F4

SFC node incorrect

82F4

SFC code inaccessible

83F4

SFC work space inaccessible

84F4

too many initial SFC steps

85F4

too many active SFC steps

86F4

SFC sequence code incorrect

87F4

SFC code description incorrect

88F4

SFC reference table incorrect

89F4

SFC internal index calculation detected error

8AF4

SFC step status not available

8BF4

SFC memory too small after a change due to a download

8CF4

transition/action section inaccessible

8DF4

SFC work space too small

8EF4

version of the SFC code older than the interpreter

8FF4

version of the SFC code more recent than the interpreter

90F4

poor description of an SFC object: NULL pointer

91F4

action identifier not authorized

92F4

poor definition of the time for an action identifier

93F4

macro step cannot be found in the list of active steps for deactivation

94F4

overflow in the action table

95F4

overflow in the step activation/deactivation table

9690

error detected in the application CRC check (checksum)

DE87

calculation detected error on numbers with decimal points

DEB0

watchdog overrun

DEF0

division by 0

DEF1

character string transfer detected error

DEF2

capacity exceeded

DEF3

index overrun

DEF7

SFC execution detected error

DEFE

SFC steps undefined

Restarting the Application

After a blocking condition has occurred, the halted CPU needs to be initialized. The CPU can also be initialized by setting the %S0 bit to 1.

When initialized, the application behaves as follows:

  • the data resume their initial value

  • tasks are stopped at end of cycle

  • the input image is refreshed

  • outputs are controlled in fallback position

The RUN command then allows the application to be restarted.