The DFB places itself into the command by maintaining the link between the application program and the action and vice versa :
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inputs REQ_O and REQ_I enable requests to be received,
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outputs ORDER_O and ORDER_I send the orders through to the operator,
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Inputs SENSOR_O andSENSOR_I and if necessary the data NOSENS_O and NOSENS_I provide the DFB with information on the physical positions of "output" and "re-input".
The movement period is checked through the dataRMIN_O, RMAX_O, RMIN_I and RMAX_I .
The inputsSECU_O andSECU_I set the safety conditions before being accepted during the "re-input" and "output" movements.
Input SECUPERM shows the operating conditions of the machine which have to be accepted during the movements.
During normal function (Reset-command mode and bit READY =1), the DFB commands the movement(s) by carrying out the following operations.
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Phase
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Description
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1
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Sensor check (inputs SENSOR_I and SENSOR_O and if necessary NOSENS_I and NOSENS_O)
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2
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Request monitoring (inputs REQ_I and REQ_O)
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3
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monitoring of the movement period
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4
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minimum and maximum latch of movement periods
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5
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training on movement periods
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6
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detecting and reacting to errors
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7
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developing the reports for the functional command
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8
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developing the operator commands (outputs ORDER_I and ORDER_O )
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9
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updating the functional indicators
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10
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aiding the cycle relaunch
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Where movement requests are not present and if on the face of it they are authorized (the "request refused" information would not be activated in STATUS0 ), the DFB positions its outputsPOSSIB_I and POSSIB_O in state 1.
NOTE:
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SECUPERM (continuous operating conditions) or SECU_O/I (movement safety conditions) become part of the bit evaluation POSSIB_O/I if their absence brings the orders down again; or in other words, if the errors included in them are selected in the mask RST_ORD .
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a movement will be refused if an error selected in RST_ORD is present at the time the request is made.
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if the reverse request is present during a movement request, its execution will always be prevented (this error can not be masked). Furthermore, during execution of a movement, a reverse request will cancel the order, whether the request is accepted or not,
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in position a request has no effect on commands of order type up to position (type 3 or 4): POSSIB takes this condition into account.
In position, the disappearance of a sensor is only signaled at the end of the time specified by DIS_TIME . This reset is disabled as soon as a movement request has been accepted.
Outside recalibration mode, the appearance of an unexpected sensor is only signaled after the time specified by APP_TIME .
The DFB positions the data which provide information on the execution of the movement :
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the outputs STATE_I and STATE_O specify the state of the movement checked by the DFB (position reached). FAULT_I and FAULT_O signal an error on the movement as it happens,
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INC_I and INC_O signal a discrepancy between the expected position (data RESEQ_I, RESEQ_O and ORIGIN ) and the outputs STATE_I and STATE_O in the absence of an order or a request,
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the internal data MVT_I and MVT_O signal that the involved movement has not yet finished (inoperative position).
During movement, the safety conditions linked to the movement and the permanent conditions have to remain enabled according to the masks RST_FB and RST_ORD.
Following an error configured in RST_FB or following a request RESET_FB, triggering off a switch to recalibration mode, the DFB performs the operations detailed below :
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deactivation of the bit READY,
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deactivation of outputs STATE_I/O and ORDER_I/O,
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consideration of its configuration data and continuation of the action if there is no configuration error in STATUS1 (only in the event of a request RESET_FB),
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pending request INIT to remove the faults which are no longer present in STATUS0 (only in the event of a fault). The DFB is then in a RESET state whereby it is "Frozen" : it no longer tests the constant conditions, the safety conditions and its outputs stop changing,
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switching to recalibration mode to relocate a source position,
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send to reset-command mode as soon as it detects a coherent sensor configuration.
Helping to resume the cycle.
The RESEQ_I, RESEQ_O and ORIGIN data inform the DFB of the state expected by the automation.
The DFB stores the last expected state (presented as 1 from RESEQ_I, RESEQ_O or ORIGIN).
If the state or the movement checked by the DFB does not match the expected state (the last one stored), the outputs INC_I and INC_O signal a discrepancy. When the DFB switches into recalibration mode, the states expected before the switch are stored.
Saving the minimum and maximum periods of the movements
For each movement executed, the DFB (in non-simulated mode) saves the period and stores the minimum and maximum periods in the TMIN_I, TMAX_I, TMIN_O and TMAX_O data.
The maximum periods are only stored if they are below the maximum reference values RMAX_I and RMAX_O. The RESET_CT data enables the minimum and maximum movement values to be reset.
Training on the movement periods,
It is possible for the DFB to learn the periods of the movements. In order to do this, the time management configuration data must be set at 0.
Whenever a movement is executed without interruption, the data RMIN_O (or RMIN_I)adopts a value equal to half of the movement period; whilst RMAX_O (or RMAX_I) adopts a value equal to 1 and a half times this value.
A movement can be said to have been executed without interruption when it has not stopped of its own accord, due either to the absence of requests for operators enabling it, or by default, which puts the commands at zero.
Once the periods of the two movements have been established, the ADJ_TIME bit adopts value 1.
Special features of the rotational movement
Position Evaluation
If the two inputs SENSOR_I and SENSOR_O (and if necessary NOSENS_I and NOSENS_O), are not identical, the "command error" fault will be signaled.
In position, if one or both of the two inputs fall back to 0, the DFB will begin to count the disappearance period of the sensor(s) and will do so until the 2 inputs readopt value 1 in the same time.
During movement, the position will be considered as "quit" if both of the 2 sensors are seen at 0 at least once. The position will be considered as "reached" if both of the sensors are seen at 1.
The only faults signaled concerning the sensor are therefore :
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in position : "disappeared sensor(s)" or "non returning sensor(s)",
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in movement : "misplaced sensor(s)" or "delayed sensor(s)",
Request maintained and position reached
In rotation only one position is checked (the two sensors are taken together). On position and conversely to the translation movement, the two requests are accepted and the two possible movements are begun.
When a movement is finished (position reached), if the "re-input" or "output" request is still present, the movement is automatically restarted. In order to prevent this with the rotation movement, the requests are interpreted on rising edge.
Execution of movements in manual mode (machine cycle inoperative) is dependent on functional command, independent of the DFB. The DFB reacts to the commands in the same way as it does in automatic mode.
However, in order for the DFB to be able to function in manual mode, it has to be executed in exactly the same way outside the machine cycle. In order to do this, if a manual command is anticipated for the DFB, it has to be executed in an easily accessible PL7 module, regardless machine cycle status: module executed during each PLC cycle (POST or SR) whose call can be controlled whilst in function or independently of the machine cycle.
Automatic operation modes
The DFB, during application transfer or cartridge replacement, resets all of its data, takes its configuration data into consideration and goes into recalibration mode (READY at 0).
On %S0 request or restart after a power outage, the DFB goes back into recalibration mode (READY at 0). The outputs ORDER_I/O and STATE_I/O are reset to 0. The counters run by RESET_CT are retained as are the reference times.
The reset-command mode will be activated when a position is found, where no fault is signaled and no request present (whatever the NEW_REQ value).
