LeCroy 9400A Manual page 133

I data-128
°fret 2°oil
20° 1
V = gain
32 25
vgain + 80
- The first expression "(data - 128)/32" transforms the unsigned data
value to a signed value, in units of vertical divisions.
- The second expression "(offset - 200)/25" translates the internal
coding of the offset into a signed offset, units: vertical divisions.
- The third expression "200/(vgain + 80)" takes into account the
variable gain. It reduces, to the value 1 when "vgain" assumes the
"calibrated" value of 120.
Examples:
gain = I00 mV byt e 0 of descriptor = 26
offset = 200 no offset
vgain = 120 calibrated gain
The formula reduces to
V = I00 mV (data - 128)/32
data volts
0 -400 mV
128 0 mV
129 3.12 mV
160
+I00 mV
240
+350 mV
255
+396.88 mV
gain = 500 mV byte 0 of descriptor = 28
offset = 250 offset = + 2 div
vgain = 20 variable gain
= .500 (equivalent to
MULTIPLYING the
vertical scale by 2)
The formula reduces to
V = 500 mV ((data - 128)/32 - 2) *
data
volts
0 -6.0 V
64 -4.0 V
128
-2.0 V
192 0 V
193 31.25 mV
200
.25 V
240
I. 5 V
255 i. 969 V
7-51
Remote Operations