VersaLogic VL-12CT96, Reference Manual

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4-2
VL-12CT96/7 Analog & Digital I/O Card
Analog Input Registers
The following table lists the functions assigned to each read and write register.
Write Registers Functions Page
CONTROL Interrupt, Auto-trigger, Auto increment, Scan range limit 4-2
SELECT Selects A/D channel to convert 4-4
CONVERT
1
Triggers A/D conversion 4-5
CLRFLG
1
Clears Done bit 4-5
PARLO Parallel Port Data Low (Opto 22 Modules 8-15) 4-12
PARHI Parallel Port Data High (Opto 22 Modules 0-7) 4-12
DAC0LO D/A Channel 0 Data Low 4-10
DAC0HI D/A Channel 0 Data High 4-10
DAC1LO D/A Channel 1 Data Low 4-10
DAC1HI D/A Channel 1 Data High 4-10
Read Registers Functions Page
STATUS Busy, Done, Settling Delay, Interrupt status bits 4-6
ADCLO A/D Data Low 4-7
ADCHI A/D Data High 4-7
1 Data insensitive. Any value may be written to this port.
Figure 4-2. Read and Write Register Functions
Analog Input Write Registers
Control Register
CONTROL — 0300H
7 6 5 4 3 2 1 0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
Figure 4-3. Control Register
The Control register is a write register used to configure the operating mode of the VL-12CT96/7.
D7 — Not Used.
This bit has no function on the VL-12CT96/7.
D6, D5 — Scan Range Limit.
These two bits define and restrict the number of channels scanned in auto-
increment mode. This allows for faster throughput when only eight or four analog signals are
connected. A “1” bit in D
6
or D
5
forces a “0” on the multiplexer address lines MA3 or MA2 respectively.
Values other than those listed will cause channels to be skipped in groups. A board reset selects (00)
so that applications which do not use auto-increment mode are not restricted to a limited set of
channels.
D6 D5 Scan Range Comment
0 0 0 to 15 All 16 channels
1 0 0 to 7 Restricted range
1 1 0 to 3 Restricted range
Figure 4-4. Scan Range Limit
Registers — Analog Input Registers