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ANALOGUE
& DIGITAL I/O
A 50-conductor ribbon cable is supplied to connect MicroDACs
to any 8,16,24, or 32 module mounting rack. If connected to
a G5 rack, any combination of analogue and digital I/O modules
may be used. Standard and Mini racks permit only a combination
of digital modules. MicroDACs can be networked to a host computer
which runs programs that monitor the input signals and control
the outputs. In addition to simple ON/OFF instructions, commands
are included which permit you to:
· Sample analogue signals at 1 mSec per input
· Flag values above or below prescribed levels
· Capture min/max values
· Calculate the average input signal levels
· Provide linearised thermocouple and RTD temperature
values
· Determine the width of input pulses
· Count pulses at frequencies up to 1000Hz
· Detect rising or falling edges
· Latch momentary input events
· Set the level of analogue outputs
· Generate square, sawtooth, triangular, or ramp waveforms
· Provide delayed-on or delayed-off outputs
COMMUNICATIONS
The host computer and MicroDAC(s)communicate serially over
one or two pair of twisted wires per RS-422/485 in either
a multi-drop or repeat configuration. They use Optomux3 ASCII
format to code the command and the response messages. Application
programs running on the host computer issue commands and then
await responses from the MicroDAC. The communications speed
is selectable between 1.2 and 115.2 KBaud. Each controller
on the network is assigned a unique base address. You can
separate units from one another by as much as 5,000 feet.
EMBEDDED
CONTROL PROGRAMS
By specifying MicroDAC(s) with the optional 64Kb of flash
memory, you can develop and download C language programs to
any of the networked controllers.
Even while
an Embedded Control Program (ECP) is running on MicroDAC,
any Optomux3 command it receives from the host will be processed
as usual, which allows you to delegate some or all of the
control and data acquisition responsibility from the host
computer. This reduces communications time and improves system
response.
For embedded
or standalone applications, downloaded ECP routines can be
initiated on power-up. Where redundant control or process
shut-down procedures are vital, ECP initiation can be tied
to the communications watchdog timer. In the event the host
computer goes off line, the ECP automatically begins executing.
Libraries
and the appropriate download utility are included with the
ECP Programmers Manual.
SOFTWARE
Software drivers are available that simplify the task of interfacing
host programs written in BASIC or C. Sample programs, set-up
and debug utilities are included on the disk with the drivers.
Interface drivers for most third party software packages are
available through their distributors. Our MicroDAC DDE Server
dramatically simplifies data sharing between MicroDACs and
Windows3.1 applications, such as Microsoft EXCEL (see Optomux
Software). Our DLL will assist you in building custom Windows
Man-Machine Interfaces using Visual Basic, Visual C/C++, or
Borland compilers.
OTHER
FEATURES / OPTIONS
The RS-232 serial port provides a connection for remote RS-232
devices. You can use this port to read information from input
devices such as bar code readers or keyboards or to write
information to output devices such as operator interfaces,
intelligent displays or printers.
The optional
real time clock permits ECP routines to be executed based
on date or time of day. It also allows data that is collected
to be time stamped and stored in battery backed RAM memory.
For more
sophisticated applications, Grayhill or third party SBX boards
can be installed under the MicroDAC cover. The ARCNET kits
can be used to enhance the communications between MicroDACs
by adding peer-to-peer capability and improving response time.
The I/O count per MicroDAC can be in creased by 48 digital
I/O with the addition of the I/O expansion SBX board.
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