14. Glossary
Terms used in this guide, in alphabetical order.
| Term | Meaning |
|---|---|
| .ftcf file | File of a custom function, with blocks, links, user screen and the hash of the editing password, if there is one (never the password text). It is used to export and import. |
| 1 kHz loop | Nominal repetition, every 1 ms, in which the VCU runs all the blocks in dependency order; each repetition is a cycle. |
| 2-step | Native launch function of the VCU, which FuelTech Vision calls 2-step rev limiter: it limits the RPM before the launch. In ignition, it wins over the custom function. |
| 3-step | Native launch function (3-step / boost spool / roll start), to spool the turbo or to launch while rolling. In ignition, it wins over the custom function. |
| Alpha | Weight of the new sample in a filter. Near 0 it filters a lot; near 1 it barely filters. It applies per cycle, not per second. |
| Anti windup | Limit of the value accumulated by the integral part of a PID, upward and downward. It prevents the accumulated value from growing without end. |
| Anti-lag | Native VCU function (in the menu, Anti-Lag / Pops & Bangs / Engine brake) that holds the turbo pressure with the throttle closed. In ignition, it ties with the custom function. |
| Bank | Group of injectors commanded together. The VCU has banks A, B and C (Primaries, Secondaries and Tertiaries on the screen), each with its own actions in the VCU action block. |
| Block | Each piece of a custom function, with inputs, output and parameters. |
| Burnout | Native launch function used in the burnout, the heating of the tires before the launch. In ignition, it wins over the custom function. |
| CAN | Communication network (CAN bus) between the vehicle's modules. A channel that arrives over the CAN bus can overwrite the value the function writes to it. |
| Channel | Value that the VCU stores and shows on the panel and in the log, such as RPM, MAP or a Custom measurement. |
| Clamp and Extrapolation | Modes of tables and vectors outside the range of the axes: Clamp holds the value at the end; Extrapolation continues the line of the end segment. |
| Closed loop | Automatic correction of the injection from the O2 sensor reading, to reach the mixture target. |
| Configuration memory | Space of 2048 bytes, for the whole map, where the type, the connections and the parameters of the blocks are kept. It appears as Settings. |
| Custom function | Program built with blocks and links that runs inside the VCU. The map has 10 slots for them. |
| Custom measurement | One of the 36 channels (#01 to #36) that a function writes with Value for VCU. The user can rename the channel. |
| Cutoff frequency | Frequency, in Hz, that sets the Low pass filter: the lower it is, the more the filter smooths and the slower the output follows the input. |
| Cycle (iteration) | Each run of the VCU through all the blocks of all the enabled functions. It happens every 1 ms (1 kHz), a nominal value that depends on the processor load. |
| Datalogger | VCU log recorder. Each channel must be enabled in it to appear in the log (Datalogger settings screen). |
| Deadband | Band around a value in which the output is 0. Outside it, the Deadband block delivers the input minus the limit. |
| Derivative | Change of a signal per second. The Derivative block divides the difference between two cycles by the time between them. |
| Dither | Small, fast oscillation added to the command of an output. In the solenoid current example, a square wave of +5% and −5% added to the duty. |
| Duty | Fraction of the time a PWM output stays on, from 0 to 100%. |
| ETC | Electronic throttle control (drive-by-wire): the throttle plate moved by an electric motor and commanded by the VCU. |
| EV | Electric vehicle. The VCU action block has two actions on the electric motor's torque target. |
| Feedback loop | Path of links that goes back to an earlier block. The editor accepts it, but the VCU does not run those blocks or the ones that depend on them. |
| Feedforward | Part of the command calculated directly from the target, without waiting for the error to appear. In the solenoid current example, it is the duty the target would require by itself. |
| Filter | Block that smooths a signal. There are EMA filter (exponential moving average), Average filter and Low pass filter. |
| Firmware | Program that runs inside the VCU. An older firmware may not recognize a block of the map. |
| Flex Fuel | Use of fuel with variable ethanol content, measured by a sensor. The Ethanol override (Flex Fuel) action replaces the sensor's ethanol %. |
| FuelTech Vision | FuelTech software that configures the VCU. The custom function editor is in the desktop version. |
| Gain | Number that multiplies a signal. In the PID, P gain, I gain and D gain are inputs of the block. |
| GDI | Direct injection: the fuel is injected inside the cylinder. The acceleration enrichment example does not suit GDI. |
| Graph | The complete drawing of a function: all the blocks and links. |
| Half bridge | Type of output that connects the load to positive or to negative (ground). On the FT700, the C pins are half bridge. |
| Hard cut | Native rev limiter of the VCU. The custom function beats it only in the fixed ignition timing that the hard cut can apply; the limiter's cut keeps acting. |
| Hash | Cryptographic digest of the editing password. FuelTech Vision stores the hash, never the password. |
| Hysteresis | Gap between the value that turns on and the value that turns off. It prevents the output from oscillating when the signal stays near a limit. |
| Interpolation | Calculation of a value between two known points of a table or vector, in a straight line. In tables, on both axes, between four cells (bilinear interpolation). |
| Jet ski control | Native function for jet ski engines (direction of travel and speed limit). On the ETC opening limit, the custom function wins over jet ski control. |
| Kp, Ki and Kd | Proportional, integral and derivative gains of a PID. In the block, they are the P gain, I gain and D gain inputs. |
| Latch | Block that keeps a state until it receives the opposite command. In FuelTech Vision: SR Latch (Set and Reset). |
| Link | Connection between the output of one block and the input of another, drawn as a line in the editor. One output feeds several inputs; one input accepts only one link. |
| Log | Recording of the VCU channels during use. Each log has the map that was active embedded in it. |
| MAP | Intake manifold pressure. The FuelTech Vision measures table declares it in bar. |
| Map | File (.ftmap) with the VCU settings, including the 10 custom functions. |
| NaN and Inf | Invalid results of a calculation: NaN ("not a number") and infinity. The VCU does not check for them or warn about them. |
| O2 sensor (lambda sensor) | Sensor in the exhaust that measures the air-fuel mixture. The lambda target is the desired mixture. |
| On-Delay and Off-Delay | Modes of the Delay block: On-Delay delays only the turn-on; Off-Delay, only the turn-off. |
| Override | Replacement of the value the native function calculates with the value of the custom function. |
| PID | Control that adds three parts of the error: proportional (P), integral (I) and derivative (D). Here the error is Data − Target. |
| Pins A, B and C | Output pin types of the FT700: A (injection), B (ignition) and C (half bridge). The electrical characteristics are in the VCU installation manual. |
| Push to Pass (P2P) | Native function triggered by the push to pass button, with its own counter. On the ETC opening limit, it wins over the custom function. |
| PWM | Signal that switches on and off many times per second. The Duty sets how long it stays on. |
| Rising edge | Instant when a signal goes from 0 (or less) to a value greater than 0. The Counter counts these edges. |
| Sample and Hold | Block that stores the value of a signal at the instant of a trigger and holds it at the output until the next trigger. |
| Socket | Connection point of a block: inputs on the left and outputs on the right. Links connect sockets. |
| Time based compensations | Native function of the Drag Race Features menu that applies corrections by time. On the ETC opening limit, it wins over the custom function; on the O2 closed loop target, the custom function wins. |
| Time constant (tau) | Measure of how slow a filter is: at 1 tau the output reaches 63% of a step. The larger it is, the slower the output follows the input. |
| TPS | Throttle position sensor, in %. |
| User screen | Screen with fields, tables and texts built in the Screen editor. With a password on the function, it is what the customer edits. |
| Value for VCU | Block that writes a value to a VCU channel. |
| VCU | FuelTech control unit, such as the FT700 and the FT470, that runs the custom functions. Some screens and messages call it ECU. |
| VCU action | Output block that asks the VCU to change a native function, for example to add ignition advance. |
| VCU value | Block that reads a VCU channel and delivers the value to the drawing. |
| VE mode | Mode of calculating the injection from the engine's volumetric efficiency, an alternative to the time-based mode. VE is volumetric efficiency; the electric vehicle, in this guide, is EV. |
| White wire input | Name of the VCU's analog inputs in FuelTech Vision. Inputs #15 to #18 share the pin with analog outputs #1 to #4 (Analog Outputs screen). |
| Working memory | Space of 512 bytes, for the whole map, where the blocks keep states and results. It appears as RAM; the VCU error message calls it execution memory. |
| Workspace | Each of the map's 10 custom functions, from Custom function 1 to 10. Some screens use this term. |
| Yellow output | Name of the VCU's half bridge outputs in FuelTech Vision (Yellow outputs screen). |