Measurement Computing Daq PC-Card - Manual (Page 50)

DaqBoards [ISA-Types Only] Daq* Hardware
3-20 Daq* Hardware 10-18-00 DaqBook / DaqBoard [ISA-types] / Daq PC-Card User’s Manual
DAC Reference Selection (JP2)
This 5×2 header (JP2) allows you to select internal or external voltage references for the two separate
analog outputs. If the internal -5 VDC reference is selected, either DAC can output from 0 to +5 VDC as
the register count varies from 0 to 4095 (12-bit). If an external voltage reference is desired (up to 10 VDC
in either polarity), the shunt jumpers must be set accordingly. There is also a provision to allow the
outputting of a simultaneous Sample-Hold command signal on the DAC1-REFIN pin with the DAC1 set up
for an internal reference.
&$87,21
The SSH setting cannot be used at the same time as a DAC1 external reference due
to a potentially damaging conflict on P1 pin #26. The defaults are both DAC0 and
DAC1 set to Internal Reference.
Note: The SSH setting is used with DBKs: 2, 4, 5, 7, 17, 50, and 51. Refer to the DBK chapter (4)
as needed.
JP 2 JP 2 JP 2 JP 2 JP 2
Fa cto ry D e fa u lt
D A C 0 E xte rn al R e f
D A C 1 E xte rn al R e f
D A C 0 E xte rn al R e f
D A C 1 In te rn al R e f
D A C 0 In te rn al R e f
D A C 1 E xte rn al R e f
D A C 0 In te rn al R e f
D A C 1 In te rn al R e f
D A C 0 E xte rn al R e f
D A C 1 In te rn al R e f
w ith S S H
D A C 0 In te rn al R e f
D A C 1 In te rn al R e f
w ith S S H
E X T
IN T
S S H
IN T
E X T
D A C 1
D A C0
JP 2
JP2 DAC Reference Settings
DMA and Interrupt Selection (JP8)
This 11×2 header (JP8) selects both the interrupt IRQ level and the Direct Memory Access (DMA) channel
for control of background data transfers. The preset default is DMA channel 5 and interrupt 10 (see figure).
•
Interrupt Selection. The DaqBoard may be set to interrupt the PC when certain hardware conditions
occur. The main board interrupt may be set to IRQ level 10, 11, 12, 14 or 15. The DaqBoard’s IRQ
level cannot be shared with any other device. Setting the JP8 interrupt jumper to OPEN can disable
interrupt assistance and background transfers.
•
DMA Selection. Direct Memory Access allows high-speed data transfer either from the ADC FIFO
or to the DAC FIFO. Only DMA channels 5-7 (of an ISA AT machine’s seven channels) are
available for the DaqBoard. Set both the DRQ and DACK jumpers to the desired DMA channel (the
DaqBoard does not share DMA channels). Set the DMA jumpers to OPEN when other devices use
DMA channels 5, 6 and 7.
JP 8
DR
Q7
DR
Q6
DR
Q5
IR
Q
1
5
IR
Q
1
4
IR
Q
1
2
IR
Q
1
1
IR
Q
1
0
DA
CK
7
DA
CK
6
DA
CK
5
1
2
2 1
2 2
F a c tory D efa ult
D M A C h a nn el 5 an d Interru pt 10
JP 8
JP 8 JP 8
DR
Q7
DR
Q7
DRQ
7
DR
Q6
DR
Q6
DRQ
6
DR
Q5
DR
Q5
DRQ
5
IR
Q
1
5
IR
Q
1
5
IR
Q
1
5
IR
Q
1
4
IR
Q
1
4
IR
Q
1
4
IR
Q
1
2
IR
Q
1
2
IR
Q
1
2
IR
Q
1
1
IR
Q
1
1
IR
Q
1
1
IR
Q
1
0
IR
Q
1
0
IR
Q
1
0
DA
CK
7
DA
CK
7
DACK
7
DA
CK
6
DA
CK
6
DACK
6
DA
CK
5
DA
CK
5
DACK
5
1
1 1
2
2 2
2 1
2 1 2 1
2 2
2 2 2 2
D M A C h a nn el 7 an d Interru pt 12
O pe n D M A O pe n In terrup t
JP8 DaqBoard DMA and Interrupt Selection