Buff Control System
Signal Specifications
Spring 2005
Author: Michael Shurtliff
Version 1.0
Purpose and Scope: To describe the signals that are required or intended to be used on the controls system
for the “Buff” hydraulic assist vehicle.
Currently, the controller specified is the Compact Fieldpoint Controller cFP2020 with the following
modules and their respective specifications:
AI 102 (qty 1):
8 analog inputs
16 bit resolution
0-120VDC or +/-20mA (with selectable gain up to +/-60mV and 0-20mA)
360 hz update rate
TC-120 (qty 1):
8 differential inputs
16 bit resolution
for all types of thermocouples or thermistor
1 hz update rate
AO-210 (qty 1):
12 bit resolution
0-10VDC, 0-20ma output
CFP-2020 (qty 1):
Control module
RLY-420:
8 output relays
0-120VDC, 1.5A or 0-250VDC 1.5A
CB-1 (qty 3):
36 screw terminals for general purpose input up to 250V with built in CJC
CB-3 (qty 1):
For thermocouple input
Input Signals:
Throttle Position Sensor:
Signal Description: Position of the throttle
Signal Source: Vehicle throttle position sensor (engine)
Source Location: top front of engine, at injector pump
Signal Type: 0-5V DC
Signal Conditioning: direct input
Signal Isolation: none unless frequency
Method of Input to Controller: AI-102
Comments: low: 1.115V
high: 4.019V
Brake Pedal Position Sensor:
Signal Description: Detects position of brake pedal
Signal Source: brake potentiometer
Source Location: brake pedal
Signal Type: DC 0-5volt
Signal Conditioning: direct input
Signal Isolation: none
Method of Input to Controller: AI-102
Comments: low: 0.1V
high: 4.95V
Rear Axle Speed:
Signal Description: This is the rotational speed of the rear axle, a currently available signal from the ABS
system of the truck.
Signal Source: Antilock Brake system
Source Location: rear axle
Signal Type: Voltage relative to speed (0-8.3V; 0=83mph, 8.3V = 83mph)
Signal Conditioning: Control Box, Speed Sensor Box
Signal Isolation: Hall Effect Sensor
Method of Input to Controller: AI 110
Comments:
All Relays:
Signal Description: Turns on and off Relays that require more amperage
Signal Source: switch
Source Location: Control Box
Signal Type: Digital (DC on/off)
Signal Conditioning: direct input
Signal Isolation: none
Method of Input to Controller: RLY-420
Comments: Relays in the system control: Tandem Valve A and B, Computer Power, E-Pump, Case Drain
Pump, Filter Pump, Control Box Power
Gear Position (or Safety Lockout):
Signal Description: Determines the vehicle’s current gear, or if the vehicle is in drive, and not park,
reverse, or neutral
Signal Source: Transmission selector switch
Source Location: Transmission Shifter Linkage by Steering Wheel
Signal Type: DC 0-5V
Signal Conditioning: direct input
Signal Isolation: none
Method of Input to Controller: AI-102
Comments: Values are Approximate
Park: 0-0.22V
reverse: 0.74-1.089V
neutral: 1.089-1.689V
D: 1.78-2.087V Gear3: 2.29-2.54V Gear2: 2.54-3.31V Gear1: 3.31-5V
Accumulator Pressure:
Signal Description: Measures accumulator pressure
Signal Source: 3-wire pressure transducer
Source Location: on header of accumulator tanks, Hydrostat Port
Signal Type: DC voltage
Signal Conditioning: direct input
Signal Isolation: none
Method of Input to Controller: AI-102
Comments: apply 5 volts to 2 wires; take output from other wire; range is 0.5-4.5volts; (0.5V=Min
Pressure; 4.5V=Max Pressure)
Fluid Temperature: (Not Currently Connected)
Signal Description:
Signal Source: k-type thermocouple
Source Location:
Signal Type: voltage
Signal Conditioning: direct input
Signal Isolation: none
Method of Input to Controller: TC-120
Comments:
Output Signals:
Hydrostat Swash Plate:
Signal Description: This is the position of the swash plate in the hydrostat
Signal Destination: Hydrostat
Device Location: Right rear of truck, mounted to frame
Signal Type: voltage output 0-2.8VDC (0-100% open)
Signal Conditioning: voltage buffer with opamp in Control Box
Signal Isolation: none
Method of output from Controller: AO-210
Comments:
A/B Switch Position (Tandem Valve):
Signal Description: This is the master hydraulic flow valve. Settings include:
Signal Destination: A/B Switch
Device Location: Above front gas tank
Signal Type: 12V DC
Signal Conditioning: Relay to control 12VDC on/off signal
Signal Isolation: relay
Method of output from Controller: RLY420
Comments:
E-Pump :
Signal Description: Solenoid Relay Wire
Signal Destination: Solenoid of E-Pump
Device Location: Above Front Gas Tank
Signal Type: Analog
Signal Conditioning: relay to control 12volt on/off signal
Signal Isolation: relay
Method of output from Controller: RLY420
Comments: Pulls about 130Amps
Case Drain Pump :
Signal Description: Turns Case Drain Pump on.
Signal Destination: Actual Pump
Device Location: Above Hydrostat
Signal Type: Analog
Signal Conditioning: relay to control 12volt on/off signal
Signal Isolation: relay
Method of output from Controller: RLY420
Comments: Pulls about 25Amps
Filter Pump :
Signal Description: Turns Filter Pump On
Signal Destination: Actual Pump
Device Location: Above Front Gas Tank
Signal Type: Analog
Signal Conditioning: relay to control 12volt on/off signal
Signal Isolation: relay
Method of output from Controller: RLY420
Comments: Pulls about 20Amps
System Status Indication: (Not Installed yet)
Signal Description:
Signal Destination: System Status indicator
Device Location: Dashboard
Signal Type:
Signal Conditioning:
Signal Isolation:
Method of output from Controller: CFP-2020 LED 1-4
Comments: