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| vetoshield:gas [2015/04/27 15:43] – [References and Additional Information] jeff | vetoshield:gas [2015/07/29 13:15] (current) – [References and Additional Information] jeff |
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| In certain situations, one or more safeties may need to be temporarily bypassed. Such is common if the pump has been left off for an extended period of time and an appreciable amount of O2 has seeped into the system near the KR and/or the O2 sensors. In this case the KR and O2 readings may be outside their limits. If the pump has not been running, these readings are not representative of the average gas quality throughout the shield. A safety can always be bypassed by setting the corresponding limit arbitrarily large or small. For example, if the KR is malfunctioning and reading very low, the KR Lower Limit can be set to 0 or some negative value that it will never reach. Alternatively, there are three override switches, one for the O2 levels, one for the pressure levels and another for the KR. Turing any one or more of these switches to ON will cause the controller to ignore the respective safeties. For example, the same problem with the KR could be addressed by instead turning the KR override to ON without tampering with the lower limit. The “Pressure Override” simultaneously bypasses all four pressure limits and the “O2 Override” simultaneously bypasses both O2 limits. | In certain situations, one or more safeties may need to be temporarily bypassed. Such is common if the pump has been left off for an extended period of time and an appreciable amount of O2 has seeped into the system near the KR and/or the O2 sensors. In this case the KR and O2 readings may be outside their limits. If the pump has not been running, these readings are not representative of the average gas quality throughout the shield. A safety can always be bypassed by setting the corresponding limit arbitrarily large or small. For example, if the KR is malfunctioning and reading very low, the KR Lower Limit can be set to 0 or some negative value that it will never reach. Alternatively, there are three override switches, one for the O2 levels, one for the pressure levels and another for the KR. Turing any one or more of these switches to ON will cause the controller to ignore the respective safeties. For example, the same problem with the KR could be addressed by instead turning the KR override to ON without tampering with the lower limit. The “Pressure Override” simultaneously bypasses all four pressure limits and the “O2 Override” simultaneously bypasses both O2 limits. |
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| Unique to the KR override is an additional auto reset switch. When this switch is turned ON, the KR override will stay on only until the reading falls within the range set by the limits or a time delay has elapsed. If the pump has been off for some time, the KR reading will likely have fallen below its lower limit and the pump cannot be restarted without turning the override on. Turning the override on with the auto reset also turned on causes the controller to ignore the reading only temporarilly while the reading is climbing back toward its normal value. The time delay can be configured by clicking on the "Limits and Setpoints" button and going to the "Advanced" tab. | Unique to the KR override is an auto reset option. When this switch is turned ON, the KR override will stay on only until the reading falls within the range set by the limits or a timeout period has elapsed. If the pump has been off for some time, the KR reading will likely have fallen below its lower limit and the pump cannot be restarted without turning the override on. Turning the override on with the auto reset also turned on causes the controller to ignore the reading only temporarily while the reading is climbing back toward its normal value. The length of the timeout period can be configured by clicking on the "Limits and Setpoints" button and going to the "Advanced" tab. Its the field labeled "KR Auto Reset Delay" and sets the maximum time the KR override will remain on. The start of the timeout period is reset whenever the override switch is toggled or when the pump is started. |
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| ===Absolute Limits=== | ===Absolute Limits=== |
| A backup of the Gas Rack folder containing the necessary controller VIs, configuration files and the executable: | A backup of the Gas Rack folder containing the necessary controller VIs, configuration files and the executable: |
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| {{:vetoshield:gasrackbackup2015-2-25.zip|}} | {{:vetoshield:gasrackbackupv2015-7-1.zip|}} |
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| The main VI (gas_rack_controller.vi) is in the folder "Controller and SubVIs" folder along with the SubVIs it directly calls. A copy of the exectuable along with the helper files is alongside these files in another folder called "builds". Some of the SubVIs outside the "Controller and SubVIs" folder are also needed while some are just testing VIs. | The main VI (gas_rack_controller.vi) is in the folder "Controller and SubVIs" folder along with the SubVIs it directly calls. A copy of the exectuable along with the helper files are inside the folder called "builds". Some of the SubVIs outside the "Controller and SubVIs" folder are also needed. There are some unused VIs. |
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| | The LabVIEW code was written in LabVIEW 2012. If using the .exe instead of the VI, LabVIEW itself does not need to be installed but you must have the LabVIEW run-time engine (version 2012f3) and DAQmx 9.4.0 installed. |
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| Also included is the firmware code to program the CPLD located on the control board located inside the blue panel: | Also included is the firmware code to program the CPLD located on the control board located inside the blue panel: |
| {{:vetoshield:mixer_control_board.jpg?700}} | {{:vetoshield:mixer_control_board.jpg?700}} |
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| ===Programming control=== | The CPLD configuration file is posted at the end of this manual along with the software written in LabVIEW. |
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| [Joe is currently in the process of finding a copy of the CPLD programming to post right here. Upon repetitive failure to find the copy, this subsection will be omitted.] | |
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| ===Software Control=== | ===Software Control=== |
| ====References and Additional Information ==== | ====References and Additional Information ==== |
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| Here is a backup containing the VIs and the configuration file needed to run the gas mixer. The top level VI is called "Mixer Control 3.vi": | A backup of the Gas Mixer folder containing necessary software needed to run the controller: |
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| | {{:vetoshield:gas_mixer_2015-7-15.zip|}} |
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| | The main VI (mixer_controllerYYYY-MM-DD.vi) is included along with the necessary SubVIs. A copy of the pre-compiled executable along with a few helper files is alongside these files in another folder called “builds”. Also included are the necessary auxiliary files the controller needs access to which are the three log text files it writes to plus the config file "gas mixer.ini" and the mail list it reads from. |
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| | The LabVIEW code was lasted edited in LabVIEW 2012. If using the .exe instead of the VI, LabVIEW itself does not need to be installed but you must have the LabVIEW run-time engine (version 2012f3) and DAQmx 9.5.1 installed. |
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| | The CPLD firmware is also included: |
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| | {{:vetoshield:gas_mixer.zip|}} |
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| | There is an up-to-date version of the .jed configuration file. The source code included is not the most recent version but is the only version I have been able to find. |
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| {{:vetoshield:mixer_backup12-13-12.zip|}} | |
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| For additional information on the gas mixing system try Joe Pastika at past0035@umn.edu. | |