This figure shows the pin diagram of the Bistable_Valve function block:
The Bistable_Valve function block is used for controlling the bistable valve.
The Bistable_Valve function block supports three operating modes:
oAutomatic Mode: The automatic mode is activated by the input pin i_xAut. In this mode, the valve is opened and closed through the inputs i_xAutOpen and i_xAutCls respectively, regardless of the local mode being activated or not.
oManual Mode: The manual mode is activated by the pin i_xMan.
Case 1: Local mode is not activated. The valve is opened and closed through the bit commands of the signal i_dwCtrl.
Case 2: Local mode is activated. The valve is opened and closed through the input signals i_xLocOpen and i_xLocCls respectively.
oLocal Mode: The local mode is activated by an input pin i_xLoc and is set additionally to the automatic or manual mode. The local mode does not influence the automatic mode, but changes the source for manual operation.
The output q_xOpen remains active as long as the feedback signal i_xFbckOpen remains low. Also, the output q_xCls remains active as long as the feedback signal i_xFbckCls remains low. This output behavior is valid for manual and local modes.
The block is de-activated on controller start and remains in the same operation mode, unless a new one is selected. If both automatic and manual modes are selected simultaneously (inputs i_xAut and i_xMan are set to 1), the operation mode is invalid which is indicated at the q_xErr output.
The position of the valve is supervised by the feedback signals i_xFbckOpen and i_xFbckCls. Once the operation is started, the feedback inputs must signal the right position of the valve within a defined time. If this time exceeds, then the block indicates a detected error. The time can be set through the structure element iFbckDly at input i_strPara.
When both open and close feedback signals are missing (i_xFbckOpen and i_xFbckCls are set to 0), and the position of the valve is unknown (QOpen_bi and QClose_bi set to 0), an unknown position error is detected.
When the input xFbckEn is FALSE, then the time supervising is NOT enabled. Refer to the Output Behavior.
The valve can be operated only if the input i_xLock is set to 0. An active interlock signal inhibits the operation of the valve. An active interlock is indicated by the output q_xLock.
The valve can only be operated if the output q_xErr is set to 0. An active detected error signal inhibits the operation of the valve.
The output q_xErr is high, only if an error is detected. The detected error can be:
oInternal detected error (invalid operation mode, missing feedback signal or unknown position).
oExternal detected error
The detected errors are indicated in the HMI as alarms. If an interlock or an error is detected during the operation of the valve, the behaviour of the function block depends on the structure element i_strPara.xFrceEn at the input i_strPara. If this element is set to 1, the block enforces the valve to move in to the default position, and the corresponding output is high (q_xOpen or q_xCls) for the duration of i_strPara.iFbckDly seconds. Otherwise the operation is stopped and has to be restarted after the interlock is gone.
To reset the q_xErr, the detected error has to be acknowledged by a rising edge on the input i_xAckn or by using bit 16 of the signal i_dwCtrl.
The default position of the valve can be set by i_strPara.xPosDflt. This description assumes Close as the default. If i_strPara.xPosDflt is set to 1, Open is the default position.
