Xycom XVME-500, Manual

Page: 54 / 104

XVME-500/590 Manual
February, 1988
Programmable Gain Selection
D7 & D6: The upper two bits of the register (D6 & D7) are used to select one
of four gain factors available in each of the three jumper-selectable
gain ranges (see Table 3-3).
Table 3-5 shows which codes are
written to bits D6 & D7 to select specific gain factors (according to
the gain range previously selected).
Table 3-5. Gain Selection Bits
Gain/Channel Register Gain Selected
D 7 D 6 Range 1 Range 2 Range 3
0 0 1 4 10
0 1 2 8 20
1 0 5 2 0 5 0
1 1 1 0 4 0 100
l
Bit D5: This sixth bit of the gain/channel register allows the register to be
used to program (initialize) gain RAM, or it allows the register to
be used to read the gain RAM
The specific channel can be programmed to apply the chosen gain
factor any time it converts a signal as follows:
1)
Write logic ‘1’ to bit D5 with a specific channel number
(as in Table 3-5)
2) Add desired gain factor from the selected gain range
(Table 3-6)
The corresponding gain factor and channel number (previously programmed) can be
read back by reading address base + 85H.
E X A M P L E S
Example 1: Programming Channel 8 For a Gain of Two
By writing 68H to the module base a 85H, input-channel 8 would be
programmed for an automatic application of a gain factor of 2 when it converts a
signal. (Note logic numbers written beneath bit numbers in Figure 3-3.)
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