Technical description Chapter 8
PA 358
25
8 FUNCTIONS
8.1 Introduction
The
PA 358
board consists of 8, 6 or 4 analog output channels.
The analog output channels are equipped with 4 D/A converters of type DAC 2815BP by
BURR BROWN
. Each D/A converter has 2 output channels.
These units generate a voltage of 0-10 V (unipolar) or ±10 V (bipolar)
without external components.
The DAC 2815BP has a 2 bytes (8+4) "double buffered" interface.
Digital data is first loaded for each channel in the "input register" (l highbyte).
Then both channels are simultaneoulsy actualised via a "latch" signal
(12-bit "latch register"). This occurs through a dummy I/O read on the base address.
This unit also has an asynchronous "clear" input, with sets both channels to "unipolar zero"
or "bipolar zero".
The value of the output channels is defined after power-on reset.
This input is also used to reset the output channels after watchdog time has run down.
Should the board no longer be accessed by software after a defined time interval (5 ms,
500 ms, 5 s), then all channels are reset.
Laser-trimmed resistors allow a 12-bit integral and differential linearity over the whole
specific temperature range, without adjusting the board (version with voltage output
channels).
Fig. 8-1: Setup (Channel 0 and 1)
Channels 2 and 3, 4 and 5 as well as 6 and 7 are identically setup.