The monitoring of faults is essential in the area of position control due to the inherent risks with moving parts.
The checks are carried out internally and automatically by the module.
The module detects 4 types of faults:
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Module faults. These are the hardware faults internal to the module. All the axes driven by the module are thus affected by the appearance of this type of fault. They can be detected during auto-tests (when reinitializing the module) or during normal operation (I/O fault).
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Hardware channel faults external to the module (for example, brake output short-circuit).
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Application channel fault linked to the axes (for example, exceeding soft stop).
The monitoring of faults at axis level is permanently active when the axis is configured.
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Commands refused channel faults. These are the faults which can appear when executing a movement, configuration transfer, adjustment parameters transfer or change of operating modes command.
NOTE: The monitoring of some faults at axis level can be enabled or disabled by the axes control parameters. These control parameters can be adjusted in the adjustment screen.
In STOP mode (OFF), the monitoring of application faults is disabled
Faults are classified into 2 levels of gravity:
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Critical or blocking faults which cause the moving part (in the case of an axis fault) or the moving parts managed by the module (in the case of a module fault) to stop. They cause the following processes:
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signaling of the fault,
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deceleration of the moving part until it stops,
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disabling of the translator, activation of the brake,
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clearing of all the stored commands,
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the wait for an acknowledgement.
The fault must have disappeared and been acknowledged for you to be able to restart the application.
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Non critical faults which cause a signaling of the fault without stopping the moving part. You must program the action to be taken with this type of fault in Control Expert.
The fault message disappears when the fault has gone and has been acknowledged (the acknowledgement is not stored and is only effective if the fault has gone).
NOTE: in the case of opening the emergency stop input, or of disabling the translator ENABLE = 0(%Qr.m.c.10), the deceleration phase is not carried out and the stop is immediate. However, the appearance of step failure information is not considered to be a blocking fault, and is simply signaled to the application.
Faults can be displayed, fixed and acknowledged from the debug screen, but it can be useful in operation to be able to drive the moving part and fix faults from a console. For this end, the application has all the necessary information and commands.
The module offers a lot of information in the form of status bits and words, which can be accessed via the Control Expert program. These bits allow faults to be handled hierarchically:
2 levels of signaling are provided:
First level: general information
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Bit
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Fault
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MOD_ERROR (%Ir.m.c.ERR)
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Channel fault
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AX_OK (%Ir.m.c.3)
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No blocking fault (with stop of moving part) is detected
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AX_FLT (%Ir.m.c.2)
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Fault (groups all the faults together)
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HD_ERR (%Ir.m.c.4)
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External hardware fault
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AX_ERR (%Ir.m.c.5)
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Application fault
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CMD_NOK (%Ir.m.c.6)
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Command refused
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Second level: detailed information
Module and axis fault status words CH_FLT(%MWr.m.c.2) and AX_STS(%MWr.m.c.3). These words are obtained via explicit exchange requests described in
language objects.
NOTE: On encountering a blocking fault, we advise you to stop the development of the sequential processing to which the axis is associated and to fix the fault by driving the moving part in manual mode. The correction of the fault must be followed by an acknowledgement of the fault.
When a fault appears:
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The fault bits AX_FLT, HD_ERR, AX_ERR and the extract bits of the status words concerned by the fault are set to 1.
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If the fault is blocking the AX_OK bit is set to 0.
When the fault disappears, all the fault bits remain in their status. The fault is stored until the acknowledgement is obtained, by setting the ACK_FLT bit (%Qr.m.c.9) to 1 (or re-initializing the module). The acknowledgement must be carried out after the fault has gone (except for soft stop faults)
If several faults are detected, the acknowledgement order only works on the faults that have effectively disappeared. The faults still present must be acknowledged again after they have disappeared.
NOTE: The acknowledgement of a fault can also be carried out on initialization of the PLC, or when a correct new command is accepted in the case of a command refused fault.
Summary table for the different types of faults
The following table summarizes the different types of fault and the associated bits:
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Channel fault
(MOD_ERROR bit: %Ir.m.c.ERR)
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Process faults (AX_FLT bit: %Ir.m.c.2)
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AX_OK: %Ir.m.c.3 (No blocking fault detected)
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Command refused (CMD_NOK bit: %Ir.m.c.6)
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External hardware (HD_ERR bit: %Ir.m.c.4)
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Application (AX_ERR bit: %Ir.m.c.5)
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|
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|
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Coding of the fault in the word CMD_FLT: %MWr.m.c.7
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(*) These faults are non blocking faults and have no influence on the AX_OK bit.
Description of the channel faults
The MOD_ERROR bit groups all the faults at channel level:
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Internal fault MOD_FLT (%MWr.m.c.2.4): module absent, out of service or in auto-test.
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Communication fault COM_FLT (%MWr.m.c.2.6): communication fault with the processor.
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Configuration fault COM_FLT (%MWr.m.c.2.6): difference between the declaration of the position of the module in the configuration and its actual position.
NOTE: The words %MW require a READ_STS command in order to be updated.
