L-1011 Trainer Installation: Digital Integration

L-1011 Trainer - Digital I/O - SO Station

Interfacing a completely analog cockpit with computers is a fascinating challenge. Generally there are a number of different types of input and output signals that need to be generated to interface with a 1970s era cockpit:

• Switch Input (which is digital in nature .. 0V for off and 24V for on)
• Annunciator and Switchlight  Output (again, these are very binary in nature ... on/off)
• Voltage Output 
• Current Output
• ARINC 429 Digital Avionics Data
• 3 Phase 400Hz Synchro Input (Analog Waveform)
• 3 Phase 400Hz Synchro Output (Analog Waveform)

These signals are progressively more complicated to generator with a computer from top to bottom. what I have been working on the last few weeks is the digital I/O interfacing of the first two categories ...  the switch input and annunciator output. 

To do so, Jim Blasco and myself are installing bus connected I/O modules into the S/O station, the overhead panel and the Main Instrument Panel. The images in the posting show the I/O modules partially installed and the cabling started. The image at the top of the posting is the set of I/O modules in the S/O station. The S/O station has by far the largest amount of switch elements. 

The two images below show the digital I/O station for the overhead and the MIP respectively. The MIP has the fewest amount of I/O switch position, however it has a good amount of annunciator lights and and elements that are requires by the Autopilot/Flight Director System.

L-1011 Trainer - Digital I/O - Overhead

L-1011 Trainer - Digital I/O - MIP