Replacing Dedicated Hardware with Commercial off-the-Shelf Customizable Hardware
Computer control systems on the Royal Dutch Navy ships are outdated. Some of these systems are still in operation, and others have been updated but use the same system architecture. The system consists of a large mainframe processor, which communicates over a special 8-wire TMIO/TMCU serial bus, with some external connected auxiliary hardware, including tape devices, memory, printers, display consoles, weapon systems, radar, and the captains’ horizontal display console.
The mainframe does not have a direct I/O console. The program is loaded from a tape or CompactFlash device and after a load command to the program is executed. To maintain, test, debug, and setup the mainframe, we implement a special-purpose portable interface computer (PICO) system that uses dedicated hardware to interface directly to the 8-wire serial bus. However, the PICO system is now outdated. We have several of PICO systems on each ship, but because we can no longer order spare parts, more and more systems have stopped functioning. Therefore, we need to replace the approximately 50 systems used by the Royal Dutch Navy and possibly for other countries that use the same computer architecture.
The main functional requirements of replacing the PICO systems include the ability to communicate via teletype/telnet sessions with the mainframe over the special TMCU bus to send messages, commands, and parameters; and to emulate devices attached to the TMIO/TMCU bus, such as tape or CompactFlash readers, to load programs to the mainframe. In addition, the systems need to be transportable and rugged so that we can take them on ships and to maintenance facilities.
We researched different solutions for replacement hardware such as a laptop with special custom hardware and PCI- and PXI-based industrial computers. However, because the navy crew does not generally use laptops as measurement devices, they also used them to check e-mail, browse the Web, and to loan to other crew members during long stays at sea. This can lead to software becoming damaged by other software installations or loss of measurement files. Both the laptop and the PCI-based solution were less rugged and lacked modularity.
On the other hand, the navy crew immediately recognized the NI PXI-1042Q chassis with the PMA-1115 keyboard and monitor accessory as a special measurement device. We can narrow the Microsoft Windows XP OS for users so they will only have access to the executable measurement application.
In addition, the PXI system is more rugged and a modular expandable PC-based platform. We can expect to obtain replacement parts for extended periods as opposed to less rugged laptop parts. We can also add functionality and modules to the system if we need to do additional tests, including serial, small computer system interface (SCSI), and GPIB interfaces, in the future.
The PXI system would be at least five times more cost-effective compared to the dedicated laptop solution because we can use off-the-shelf LabVIEW FPGA technology to interface with proprietary protocols. Furthermore, the laptop would need expensive custom-built hardware.
Developing the Application
We developed applications for field-programmable gate arrays (FPGAs) using the LabVIEW FPGA Module. The application consists of an input task; output task; protocol conversion to TMCU from teletype/loading of test software commands; and front ends for tasks like telnet, software loading to the mainframe, and other tasks – all running on the FPGA.
Because most of the original system developers no longer work at the supplier, we are missing vital information including source code, functionality information, commands, and protocols.
We used the NI PXI-7811R module to log messages during communication between various devices. We conducted a reverse engineering process and determined the low-level commands and data-packet size so that we could emulate these devices. For example, we can detach the CompactFlash program loader, load our test program into the mainframe, and instruct it to do a memory test. This test is comparable with a test to a desktop PC in which we disable all external and internal devices, such as the hard drive. Then we can boot via our PXI system and emulate the hard drive to more easily find errors and debug the system for faulty cards because we can switch off function by function and run past test programs.
In addition to emulating devices and interfacing over a telnet-like interface with the mainframe, the LabVIEW solution has remote debugging advantages. For maintenance purposes, we plan to use the built-in LabVIEW Web interface for remote debugging from the shore while the ship is at sea. We can also quickly look into the system. In this mode, the PXI system logs all message data to and from the mainframe and performs real-time analysis on them. In the past we needed a special program that stored the data on CompactFlash. To retrieve the data, we needed to shut down the mainframe, extract the data from the CompactFlash, and start the mainframe again.
Accurate Shooting with a Weapon System
Another big benefit of the PXI system is that we can now monitor the bus traffic, quickly look at all navy systems, and analyze test firing runs with drones in real time with logging and real-time analysis. The goalkeeper defensive weapon system can autonomously track enemy missiles, ships, and aircraft by radar and then fire up to 4,200 bullets/minute. During a test firing, a drone is pulled by an aircraft flying toward the ship. In the past, it was difficult to quickly analyze these tests because the ship sails at specific coordinates, the radar system reports in polar coordinates relative to the ship, and the gun reports in x/y coordinates. We recorded of all this data offline, which was very time-consuming. Now we can use PXI to log all of the goalkeeper messages, incoming ship information, and radar in real time to view how much the drone flight is aligned with respect to the preferred drone flight path. Now the captain can view the test results as the aircraft turns.
The extensive functionality of LabVIEW allowed us to transfer coordinate systems into other coordinate systems with the presentation capabilities and PMA-1115 as key factors. We also substantially reduced test time. In addition, the portable monitor and keyboard accessory provided us with the portability and flexibility we needed to equip our entire fleet with a dependable LabVIEW and PXI-based solution. Our naval engineers and technicians are very satisfied with the ease of use and performance of the NI FPGA PXI-based systems. System advantages include the extensive and broad LabVIEW functionality, such as conversion of coordinate systems, built-in Web interfaces, and more.
With previous programming experience using Microsoft Windows OSS to develop our applications, we were able to quickly develop the custom communication protocol on the PXI-7811R module because the programming paradigm is the same. We plan to extend the functionality of the PXI system to other areas in the future.
Richard Van Der Weide
Royal Dutch Navy
Het Nieuwe Diep 5
Den Helder 1781 AC
Tel: +31 (0223) 656 921