Automatic diagnostics of switches of pneumatic transportation system

The article dwells on the up-to-date issues of the automatic microprocessor-based diagnostics of the automatic switches, which are a part of the pneumatic sample capsule transportation for an assay with the maximum use of the automatic control devices. A structural diagram of the pneumatic transport system has been developed. The article deals with the functioning of the main components of the pneumatic transport system. An algorithm for the functioning of the microprocessor control system in the diagnostic mode is developed and the structural diagram of the algorithm is shown. A scheme of a microprocessor control system for the components of a pneumatic transport system has been developed.


Introduction
The automatic switches are used in the pneumatic transportation system of the pneumatic representative sample capsule transportation for an assay and ensure optimal routing of the pneumatic capsule delivery for an assay of controlled engineering products [1]. Systems for pneumatic sample capsule transportation for an assay are a part of automated analytical control of products manufactured at ore dressing and metallurgical plants [2].

Main section
The system for automatic pneumatic representative sample capsule transportation for an assay consists of the following main units [1,2]: -Stations for automatic charging (SCS) of an averaged sample into a capsule and conveyance of the capsule with the sample to a quick assay laboratory; -Stations for automatic discharging (SDS) of the process samples from the capsule and automatic return of an empty capsule to a sampling point; -A transport piping system between the sampling points and the analytical laboratories making assays; -Automatic switches (SW) that are used to change the direction of moving loaded capsules automatically from the automatic charging stations of an averaged sample to the central pipeline, which is connected to the automatic discharge station of the process samples delivered for an assay from the capsule and return of empty containers after their unloading.
The structure of stations (SCS, SDS) and automatic switches (SW) includes control systems (MCS). Information signals are transmitted between control systems. conveying system is controlled by the central control system [2]. The central control system (CMCS) controls the direction of movement of the container. The CMCS generates the signal "Start", which is sent to the devices of the pneumatic transport system, which must work at this time. The devices of the pneumatic transport system, having completed the work, send an information signal "End" to the CMCS. The design and operating principle of the automatic sample charge station in the capsule is described in [11] and [2].
The operating principle for the switch is described in the monograph [1] and depicted in Figure 1. The operating experience of the effective automatic pneumatic system of the capsule transportation for an assay allowed for developing and implementing the automatic microprocessor-based system for diagnostics of SW performance, which algorithm can be seen in Figure 2.
The program that runs this algorithm is introduced into the universal standard systems of microprocessor control [2] and uses information about the condition of own magnetic pick-ups (MP) of the piston location of the air cylinders.
The developed algorithm of the automatic technical diagnostics of the performance of the automatic switch can be implemented every time the pneumatic transportation system is turned on or at any time of its operation based on the request from the operator servicing this system.
The results of technical diagnostics of automatic SW performance (lack of necessary information signals from the magnetic pick-ups) can be seen on the relevant display boards, which allow the maintenance staff to identify a malfunctioning unit quickly. In the absence of malfunctions, the display board shows a relevant message (ready SW), and the control system automatically proceeds to implementing the basic algorithm of the pneumatic transportation system operation.
The basic mode of operation is shown in Figure 3. The circuit diagram of the microprocessor-based control system and automatic technical diagnostics (MCS) of the automatic switches (SW) of the pneumatic transport system, which can be seen in Figure 4, have been designed considering the foregoing.    The circuit diagram is based on the microchips, namely: DD1-microcontroller (PIC16F84A); DD2-logical elements I-NE (CD4011A); DD3, DD4-I/O devices (NTE8255).
The circuit diagram has hardware redundancy to enable connection of additional sensors and devices, and thus expand functional capabilities of the capsule sample delivery system.
The information needed for operation of the control system comes via contacts of the XS1 connector. The information comprises commands generated by magnetic pick-ups (MP i).
Contacts of the connector XS2 are intended for connection of electro pneumatic distributors (EPD i) and valves (EPV i.). The information signals shown in the figures provide interaction between the devices of the transport system. The information signal "Ready" is generated by the devices when they are ready for operation.
Information about potential abnormal conditions in the controlled devices is the output on the contacts of the connector XS3. This information is controlled by MCS and when the basic mode algorithm is executed.

Conclusion
The designs, schematics and algorithms developed and discussed in this article are universal and can simplify the processes of the pneumatic transportation equipment set-up and maintenance. They can be widely used to design sample pneumatic delivery systems for further analysis, aimed at optimizing the processes at mining, ore dressing and metallurgical plants.