Chapter 2 QAS Components

Transcription

1 Chapter 2 QAS Components Chrysler In This Chapter Overview AVI/VMS Reader Empty Carrier Photoeye Floor QAS PLC Encoder Very High Speed Counter (VHSC) Module QAS Workcell Configuration Database Server Tool Controller Intelligent Work Stations PanelViews Video Camera/Monitor 1 of 16

2 QAS Components Overview Introduction The components of the QAS will be covered in detail. The basic component uses and functions will be covered in this chapter, while system connections and communications will be covered in a later chapter. Notes: 2 of 16

3 AVI/VMS Reader The AVI/VMS reader is a fixed or hand-held scanner used to read jobmounted bar code labels, decode the scanned information, and forward the information to the tracking image logic within the PLC. Through laser scanning, manual data entry errors are eliminated, ensuring faster, more efficient data transmission. Bar code readers are also used to read labels on vehicle components such as the engine. Hand-held scanners are used where mounted scanners are impractical, or they are used as backups to mounted scanners. Flow The bar code is sent to the AVI/VMS driver located in a PLC associated with that particular point. The AVI/VMS driver validates the bar code label and attaches the vehicle attributes to that bar code label. This label is then sent to the QAS Tracking Image Application, where it is used to establish a vehicle-tracking image. Attached to the AVI/VMS controller is a set of stack lights that tell the operators the status of the signal and if the label was read (blue), the label data was sent to the PLC (green), low performance has read (yellow), or if there was a No Read (red). AVI/VMS readers read bar codes at several different locations on a vehicle during the assembly process. The bar codes can be located on the vehicle frame or on the windshield. Barcode Readers and Associated Stack Lights Continued on next page 3 of 16

4 AVI/VMS Reader, Continued Windshield AVI/VMS Fixed Readers Door Line Hand Held Scanners 4 of 16

5 Empty Carrier Photoeye The empty carrier photoeye determines if there is an empty carrier. If an empty carrier passes the photoeye, the photoeye sends a signal to the AVI/VMS driver that there is no vehicle on the carrier. A No Read condition occurs, but is a normal situation. The photoeye will be reset by the AVI/VMS driver, which will look to detect a vehicle on the next carrier. If the carrier has a vehicle and the AVI/VMS driver receives no data from the reader, a No Read situation occurs and the bar code may need to be manually entered. The AVI/VMS driver sends a No Read signal to AVI/VMS WCC and the tracking image application within the PLC. A No Read signal will cause the conveyor to stop. Empty Carrier Photoeye 5 of 16

6 Floor QAS PLC The Floor QAS PLC contains the QAS Tracking Image Application and the AVI/VMS driver used by QAS. For most new conveyors, the tracking image will be designed into the conveyor PLC. A Floor QAS PLC capable of supporting several tracking images will be used where it is not possible to install the image directly into the Conveyor PLC. Flow The Floor QAS PLC receives the bar code label data from the AVI/VMS reader, then the bar code data is sent to the AVI/VMS driver. The AVI/VMS driver sends the bar code label data to the QAS Tracking Image Application. The encoder sends its signal to the Floor QAS PLC by way of a very high-speed counter module (VHSC). The encoder counts are combined with the bar code label to establish a tracking image within the Floor QAS PLC. The number of encoder counts received by the VHSC determines the position of the jobs along the conveyor. The Floor QAS PLC sends the tracking image to the QAS WCC for every 1-foot of travel on the conveyor. 6 of 16

7 Floor QAS PLC Panel 7 of 16

8 Encoder The encoder is a device that uses the mechanical rotation caused by the conveyor movement to produce an electrical signal. The electrical signal of the encoder is converted to feet, which is used to determine the distance the conveyor has traveled for vehicle position. Flow As the conveyor moves, it causes a friction wheel to turn. The friction wheel is directly coupled to the encoder. The encoder and the friction wheel generate an electric signal. This electric signal, when combined with an initial tracking image, monitors the position of a vehicle along a conveyor. Each conveyor segment has two encoders, which are wired to separate inputs. The encoders are designated as primary and backup encoders. The encoder signals are constantly compared to verify that both are functioning properly. If the primary encoder fails, then the backup encoder will automatically assume the role of the primary encoder. The loss of the primary encoder will also cause a warning signal at the Floor QAS PLC. Loss of both encoder inputs to the Floor QAS PLC will stop the conveyor. Notes: Continued on next page 8 of 16

9 Encoders, Continued The following pictures show two variations of encoder mountings. Ceiling Mounted Encoder and Friction Wheel Skillet Conveyor Encoder 9 of 16

10 Very High Speed Counter Module (VHSC) The VHSC module performs the high-speed count of the encoder pulses. The module is an intelligent block transfer I/O module that interfaces with the Floor QAS PLC. Flow The VHSC module block transfers encoder counts from the module s memory to a designated area in the Floor QAS PLC processor data table using Block Transfer Read (BTR) instructions. The VHSC module counts encoder pulses because of the high rate at which the encoder sends its pulses. There is a chance that pulses could be missed if they were sent as a direct input to the PLC data tables, as the scan time of the logic may be too long to detect each pulse. Block transfers are the standard interface for PLC modules. The tracking image logic within the PLC logic is also responsible for configuring the VHSC module by using Block Transfer Write (BTW) instructions. VHSC Module 10 of 16

11 QAS Workcell The QAS WCC is a PC dedicated to running the QAS SoftLogix5 engine. The SoftLogix5 engine is a software implementation of an Allen Bradley PLC-5. The QAS SoftLogix5 engine is run in a Windows NT environment and is responsible for reading from the Realtime Database and maintaining the tracking image within stations according to the database configuration. The Realtime Database is installed in the QAS WCC. The QAS WCC is responsible for sending job arrival messages to PFCS, where they are married to tool data for the appropriate station. Arrival messages are also sent to PFS, where they are used to sequence terminals and to trigger other functions. 11 of 16

12 Configuration Database Server The configuration database server contains the configuration database used to update the Realtime Database. The Configuration Database specifies the location of stations, tools, and terminals along the line where arrival messages are to be generated. It also identifies warning points, conveyor interlocks and annunciation device locations for ALS stations. This editor can be installed on any workstation that has Ethernet access to the configuration database server. The Configuration Database is updated with conveyor, station, and tool specific parameters, and this data is synchronized with the Realtime Database in the QAS WCC. This allows QAS to be active while updates are being made to the database. The only downtime would be during the synchronization period (approximately 5 minutes). 12 of 16

13 Tool Controller Tool controllers gather input data from station tools and send this data to PFS through PFCS. Flow Tool data is sent to PFCS, where it is married with the ID of the job received from QAS. This marriage is sent to PFS for logging. Tool Controller 13 of 16

14 Intelligent Work Stations Intelligent work stations, or desktop PCs, are used by QAS to update and configure the QAS WCC SoftLogix5 engine and the configuration database. QAS Workcell Requirements The workstation used to interface with the SoftLogix5 engine must meet several conditions to connect and communicate with the engine. These conditions are: It must operate in a Windows NT environment for the proper software to be installed. RS Linx must be installed. RS Logix must be installed. These programs allow the user to view the interface screens for the SoftLogix5 engine and to make any necessary changes. Configuration Database Requirements The workstation used for configuring the configuration database must have the Java configuration database editor program installed. This program can operate in either a Windows NT or a Windows 95 environment. The workstation uses Java Database Connectivity (JDBC) to communicate with the configuration database server. Because the configuration database server does not use JDBC, there must be a conversion to a format that the configuration database server understands. This format is Open Database Connectivity (ODBC). A Sequelink server does this conversion in the configuration database machine. 14 of 16

15 PanelView PanelViews provide the user with an array of screens that display tracking image information, such as bar code numbers and location on the conveyor in feet. Purpose Operators can use this information to verify that the proper vehicle is in station and to back up reader input in the case of a fault or No Read condition. Manual entry of job data can be performed at the PanelView. PanelViews communicate with the Floor PLC for all information requests and use block transfers to send and receive information. PanelView and Associated Control Panel 15 of 16

16 Video Camera/Monitor The camera is positioned to display the bar code. In the event of a No Read, the line will stop and the label will display on the monitor, allowing the operator to manually enter the number on the PanelView. Video Camera/Monitor 16 of 16