IO Commander

Controlling your Model Railroad from a PC.

Rev. October 97

Switching version 2

Hardware :

Version 2

One 8 bit parallell port are used to controll up to 127 switches. Version 2 consist of two different PCb's. A decoder Card with switch protection current limiter and a driver card with support for 8 switches. You need to add one driver card for every eight switch
Version 2 Hardware are identical to version 3. Hovewer some of the functionality of the decoder card are not used.

Component list for SWP128R1 for version 2
IC3	7805 5V	positive voltage regulator
IC4	74154	4 to 16 decoder
D1 - D4	1N4001	Diode
C1,C2	2200uf	Electrolytic condensator 35 Volt
R1	270 ohm 2 watt	resistor
R8 - R15	1K ohm 1/4 Watt	resistor
R16,R17	10K ohm 1/4 watt	resitor
DB25	male plug	for parallel Printer Port

Building Instructions

Do step 1 to 4 of the version 3 instructions, but you do not have to mount unused components.

Component list for SWP128R1 for components NOT used in version 2
R2,R3	82 ohm, 1 watt	resistor
IC1,IC2	4N25	Opto coupler
R4 - R7	1K ohm 1/4 Watt	resistor
T1, T3	BD135	NPN Power Transistor
T2, T4	BC546	NPN Transistor
R16,R17	10K ohm 1/4 watt	resitor

Next step is connection DB25 plug. Look at version 3 schema but connection should be from left:
(nc nc nc nc 25 5 4 3 2 nc nc 9 8 7 6)

Connect 16 volt AC as in version 3.
Do not do the single switch turnout test
Connect Turnout Driver Card as in version 3 except that line 6 should be connected one connection to the left compared with version 3.(The reason for this is that you will loose one switch of the first driver card (address 0 and 1)
Connect switch machine return wire to +20 Volt (Yes this is correct - The driver cards sends a grounding signal) This is available at connector three from left upper corner of decoder card. Switch 1 reset should be connected to The lower left of driver card. Switch 1 set signal should be connected to 2nd left, Switch 2 reset to 3rd etc.

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