PI C-844
========

Serial communication using the GreensSpring XM Octal I/O.
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The GreensSpring XM Octal I/O has a 16 pin jumper block for each serial port.
Assume (the manual does not define this) that the jumper pins are numbered
from, top to bottom, and from left to right; i.e.,
    1  2  3  4
    5  6  7  8
    9 10 11 12
   13 14 15 16
   
Then the "Default jumbering ..." depicted in Fig. 2 of the GreensSpring XM
Octal I/O manual is jumpered as follows; 1-5, 2-6, 9-13, 10-14.

The correct jumpering for the C-844 is; 1-2, 5-6, 13-16.