CONTROL SYSTEM
COMPUTER DESCRIPTION
A total understanding of the following concepts is not essential to properly maintaining and troubleshooting the Komatsu truck control system. This information is presented as additional background information con- cerning operation of the FL275 panel computer and software programs required for operation. The techni- cian should however, become familiar with basic oper- ation of portable, MSDOS operating system computers (PTU) and must have the ability to use the menu oper- ated software described later in this publication. These skills are necessary for programming the FL275 panel computer, troubleshooting, and obtaining statistical data.
Microprocessor
The microprocessor, located on the FB101 card (or FB144 card on later model trucks), contains the logical elements necessary to perform calculations and to carry out stored instructions. It is used as the central processing unit (CPU) of a computer. Computer opera- tion is managed by a software program, which resides in the computer's memory. The software program also contains instructions to test and fault isolate the sys- tem.
A program is a sequence of specific instructions in an order that, when the microprocessor executes them, proper results occur. A program is generally stored in a read-only-memory (ROM). To execute the program, the microprocessor reads an instruction from ROM, inter- prets the instruction, performs whatever task that is dic- tated by the instruction, and then starts the process over again by reading a new instruction from ROM. The microprocessor utilizes address, control, and data buses to accomplish the above process. A bus is a group of wires or circuits that collectively serve a simi- lar function. For example, the address bus identifies the location that the microprocessor is reading from or writing to. The data bus provides a path for the flow of data from one point to another. The control bus is somewhat different from the other two buses in that each wire normally serves a separate and generally unrelated function used to control the actions of the system.
While executing the program, reading and writing of data is often necessary. This data is stored in a ran- dom-access-memory (RAM). A RAM is a temporary storage device, that is, if power to the RAM is lost, the data is cleared. The RAM stores all types of data, such as, input/status from external devices, fault information, specific program addresses, etc.
The final result is to provide instructions to external devices that tell them when and/or how to operate. Throughout the execution of the program, the micro- processor acts like a traffic officer; taking in instruc- tions, interpreting them, and acting accordingly in order to process instructions to the output.
Download Capability
The computer can be reprogrammed by “downloading” new software into its memory. Downloading refers to transferring software program instructions from the PTU to the FL275 panel FB101/144 card through the serial port connector cable. This capability allows the system software to be changed if any new hardware or software option is to be installed or if an updated ver- sion of the existing software is to be implemented.
SOFTWARE
“Software” refers to computer programs written using coded instructions that can be understood by the CPU. The following is a brief description of how the software establishes and regulates propulsion and retarding.
Base Monitor Program
The Base Monitor Program performs functions for the system, including power-up tests on the CPU card. This software is programmed on four Eprom chips at the factory and installed on the FB101/144 card.
Runtime Monitor Program - OBJRunning Code
The Runtime Monitor Program is used to control com- mon truck functions. It is downloaded to Flash (Electri- cally Erasable Read Only Memory) chips on the CPU card from OBJ files stored on the PTU hard drive. This is done initially during factory check-out and can be redone in the field using the PTU.
After being downloaded to Flash, it is then copied to RAM (Random Access Memory) chips on the CPU card at system power-up.
This software:
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Controls contactors, relays, lights, solenoid, firing pulses, etc.•
Monitors truck running parameters and stores event/fault data for later examination.•
Communicates with the PTU to display operating parameters and event/fault data.E2-6 Electrical Propulsion Components 2/02 E02016
Configuration Software - CFG
The CFG program is used to set values which are spe- cific to a particular Komatsu truck model, such as engine, alternator and wheelmotor configuration, retard current limit, speed taper, power reference and control stability constants.
The operating software that controls current, voltage and horsepower limit in propulsion and current, speed taper and field amps in retarding uses a set of con- stants and look-up functions unique to and consistent with the configuration on each Komatsu truck model. The CFG program is also used to set values which are specific to a particular mine, such as overspeed set- tings.
“Configuration software”, also sometimes referred to as “configuration download software”, allows the end user (mine) or Komatsu Distributor to select, via an easy to use, menu driven program screen, any one of a num- ber of pre-recorded configurations stored in the PTU software. All the user has to do is select the configura- tion file that matches the truck being serviced.
The available combinations have been pre-recorded to be consistent with and ensure proper limits on the com- ponents used in that system. Thus, the Mine personnel do not have to be concerned with questions such as: “Is this the correct current limit for a GE776 or GE772 wheel?” or “Will speed taper in retarding work properly if I use a wheel with 23:1 gear ratio?” The configuration software will ensure compatible combinations of parameters.
The Mine technician must select or create the correct CFG file to match the truck.
The CFG program is downloaded to Flash chips on the CPU card from CFG files on the PTU hard drive. This is done initially during factory checkout, and can be redone in the field using the PTU.
NOTE: This MUST be done if the FB101/144 card is changed
PTU - Portable Test Unit Code
The PTU program is used to enable menu driven view- ing of truck data in the CPU while the truck is moving or stationary. Using the PTU, it can also be used to view and change contactor positions.
It is also used to establish a communication link between the PTU and the CPU to download OBJ and CFG software files.
The PTU program is loaded onto the PTU hard drive using GE/Komatsu supplied floppy disks. Instructions for loading this software onto the PTU and download- ing to the CPU are discussed later in this section.
System Regulation
The micro-processor, located on the CPU card (17FB101 or 17FB144), in the FL275 panel is set up electronically with the use of a Portable Test Unit (PTU) when the software described previously is downloaded. After being set up, certain operating parameters can be changed to “fine tune” the system to a particular road profile.
In addition to establishing propulsion and retarding cir- cuits and regulating truck speed and retarding, the soft- ware restricts the control system from certain transitions under certain conditions. For example, the system will not allow a direction change while in the retard or propulsion without passing through the
“nomo”, or “no motion” state. The software does,
however, allow transition among the three retard states when in retard, these states being retarding, retard
speed control and overspeed. These transitions are
allowed because, once the contactors are in the retard position, no other contactor changes are necessary. NOTE: The term “nomo” is a state which is entered at a truck speed of 0.30 mph or less.
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Propulsion
As part of the total software package, a particular group of regulatory software commands is included called a “state machine”. The state machine controls the various operating functions of truck operation. The software implements the state machine by keeping track of which state the truck is in, and which state the truck is allowed to move into if the operator requests a different mode of operation.
For example, assume the operator has turned the key switch On to start the control system software, and then starts the engine. When the accelerator pedal is pressed to request contactor sequence and excitation, the state machine enforces a sequence of actions. First, the software initializes the system. This includes ensuring that the contactors are all positioned correctly. (Initialization takes about 8 seconds after control power has been applied to the FL275 panel.)
Then, when the initialization is completed, the state becomes the “nomo”, or no motion, state. No propul- sion or braking contactors are picked up.
Next, the state machine enters the “into accelerate” state. This state can only be entered if there are no restriction flags set in the software such as brake (ser- vice or park), ACCINH, DUMPBS, NAFLT, or GNDFLT. In this state, contactor sequence is initiated. If all con- tactors necessary for acceleration are in their correct positions, then the state machine enters the ”acceler- ate” state. If the contactor sequence does not complete successfully, then a fault, NAFLT, prohibiting accelera- tion is tripped.
When the state machine enters the “accelerate” state, firing commands can be issued. Firing commands are based on operator request and truck volt and amp feedbacks. They are used to generate a pulse burst fir- ing signal from the CPU. The Alternator is thus excited, generating electrical power (horsepower) to the wheel- motors which will drive the truck forward or backward, depending on the position of the selector switch.
Retarding
When the operator presses the retard pedal, accelera- tion is canceled and the propulsion contactors are dropped out. The state machine enters the “coast” state and then the “into retarding” state. It remains in this state until all of the contactors necessary for retarding are in the correct position.
The state machine then enters the “retard” state. Fir- ing pulses are issued to the static exciters based on operator request and on various system feedbacks.
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2-DIGIT DISPLAY PANEL
The 2-Digit Display panel (Figure 2-1.), located in the control cabinet, consists of the following:
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Two digit “event” number display,•
“First” LED•
“Last” LED•
“Previous (up arrow) search key•
“Next” (down arrow) search key•
“Reset” keyUnder normal operation, with no events having been recorded, the 2-Digit Display Panel will display only two zeros (00). The “first” LED and the “last” LED will be dark (not illuminated). The “previous” and “next” search keys will be illuminated (green). The “reset” key will also be illuminated (red).
NOTE: The terms “event” and “fault” are used inter- changeably to indicate a system occurrence which has been recorded into memory. The system recognizes each as an event, that is, a fault is nothing more to the system than an event. Some events (or faults) result in restrictions being placed on truck operation. Therefore, when discussing a fault situation, the term “fault” seems more appropriate and less confusing.