Addition of the network option to APU102 requires modification of the interrupt mapping on the COM4 board to utilize shared interrupts. Previous hardware versions required that each com port in the APU had individual interrupts. The network version of the hardware will not operate with individual interrupts.

Required Materials and Tools

Upgrade Parts Required

IRQ cable (2 connector, CBL-151-1124G)
“COM4N” ejector tab or sticker
3-4 jumpers

Tools/supplies Required

Antistatic (ESD) wrist strap

Optional

UART Chip Replacement on COM4 and COM4A Boards

Caution

Follow proper antistatic precautions when handling the boards.

COM4 to COM4N Modification Procedure

1. Verify UART chip on COM4 is Texas Instruments (TI). Replace if necessary. Refer to document 376-0018-00.

2. Remove all jumpers from J15, J16 and J17 including wire-wrap jumper from J17 3-6.

3. Add the following jumpers. Refer to figure 1 for location:

J15

1-2

3-4

5-6

J16

1-2

J17

5-6

4. The Hardware Watchdog MUST be enabled. Verify the jumper J18 is installed.

5. Remove the COM4A ejector tab (held with press-pin) and replace with a COM4N tab or apply COM4N label to existing ejector tab.

6. Replace 3-position IRQ cable, CBL-151-1124F, with 2-position IRQ cable, CBL-151-1124G.