Dodge Bus PCI incorporation

[Gctech]

Im working on  PnP kit for a 2005 dodge srt4 I have sniff and define all Bus PCI communication for Dash,ABS,AC communication like RPM,Speed,Temp,TPS just to name  few ,   now this system is a SAE J1850 VPW, an transmits data at 10.4 KBps, Can any of the G4X units able to transmit in that low rate?

thanks 

A brief description of how the Bus PCI system works;

Introduced in 1998, replaced CCD as a Body Protocol. A vehicle will have either CCD or PCI, not both and PCI is a Single Wire Network. PCI Bus Speed 10.4 kbps and can support up to 32 modules or nodes. It is used as a global OBD-II scan tool interface.

PCI Bus 

A PCI bus shorted to power or ground will cause a total loss of bus communications
A loss of power or ground to an individual node should not affect bus communication. Only that module should be effected. However, an open ground could cause a back feed of voltage to the rest of the bus, potentially interrupting communication to the whole bus. Resistance values determine the module’s dominance on the bus. The lower the resistance, the higher the priority of the module.

• PCM 1000 ohms
• SKIM, ABS, SIR, EVIC 10,500 ohms
• DLC 11,000 ohms

These are typical values and should not be used for actual diagnosis. Actual specifications can be found in your service information system. Here are some tips to remember when testing these PCI circuits.

• Some applications use conventional splices to connect modules to the bus
• Splices can be located anywhere on the vehicle
• In some applications, the BCM acts as a hub for the bus
• Unplugging BCM connectors can help isolate problem modules
• Some applications use a Diagnostic Junction Port (DJP)
• Acts as a centralized splice for the bus
• Every module connected to the DJP can be diagnosed from this location

1. Frame
2. Start of Frame
3. Header Message
4. Data Byte(s)
5. CRC Byte
6. In Frame Response bytes
7. End of Frame

Each module can transmit and receive data simultaneously.
A PCI Bus message typically has the following four components:

Message Header - Is one to three bytes in length.
This contains the message type and length, priority, target module(s) and sending module

Data Byte(s) - This is the message that is being sent

Cyclic Redundancy Check (CRC) Byte - This byte is used to detect errors during message transmission

In-Frame Response Byte(s) - If a response is required from the target module(s), it can be sent during this frame

The PCI bus on which we’re focused in this article replaced Chrysler’s earlier two-wire CCD network,
which communicates at slightly less than 8 Kbps.

The PCI is a one-wire network (usually a yellow wire with a purple stripe or vice versa)
that utilizes the slower of the two SAE J1850 protocols (about 10.4 Kbps) switching
between low and high voltage levels to generate signals.

PCI bus low voltage is around zero volts, and high voltage is around 7.5 volts (half of charging system voltage).

The low and high voltage levels on a PCI bus are generated by means of variable-pulse width modulation to form signals of varying length (see illustration).
Each up or down square is a “bit,” and the bus can communicate with up to 10,400 of these pulses every second.

It’s almost insulting to share the obvious fact that you can’t measure these signals with a meter;
use a good fast O-scope set to the 20 volt scale reading in milleseconds.
If the bus is shorted to power or ground, the scope trace will tell the tale with a dead flatline, either at 12 or 0 volts.

PCI Bus messaging uses Variable Pulse Width Modulation (VPWM).

What that means is that both the state of the bus and the width of the pulse are used to encode bit information.
A zero"bit is defined as a short low pulse or long high pulse.
A one bit is defined as a long low pulse or a short high pulse.
A byte is a series of bits. Imagine bits as letters that make up words and bytes as words that make up a message.

[Adamw]

Although there is a general purpose com port on the new processor that can do most types of automotive comms such as LIN etc , you still need the appropriate hardware transceiver after that to interface with any bus.  

PCI is not something that has been requested before so support for that is not on the road map at present.  You would probably be better to do it with your own micro and transceiver, like we do on the Altezza plug-in ECU - talking to the ECU via CAN bus, then converting/relaying that to the chassis protocol.