Measurement Computing WBK40 - Manual (Page 18)

Asynchronous I/O Operations - WBK41
The WBK41 allows asynchronous input of any counter or digital channel that is not currently configured
for synchronous acquisition. The unit also allows for asynchronous output to any DBK46 D/A channels
that are not currently configured for waveform output. Note that the DBK46 is an option that must be
installed for this to be true.
Likewise, all 40 Digital I/O channels (16 from front panel terminal blocks and 24 from the rear panel P2
connector) can be used for both asynchronous input and output operations. In addition, the Timer Outputs
(from a front panel terminal block) can be programmed at any time, regardless of the current state of
synchronous or asynchronous operations on other channels.
Digital I/O Channels
Rear Panel P2 Connector, 24 Bit Digital I/O
The devices have an implemented Intel 8255 core in the digital I/O logic on the P2 port. With the Intel
8255 there are three 8-bit wide ports available for I/O and one 8-bit wide port for configuration purposes.
The configuration port is used to configure the other three 8-bit ports for either input or output operations.
Front Panel, Terminal Blocks, 16 Bit Digital I/O
The WBK41’s front panel terminal blocks include a 16-bit Digital I/O port. With this port, no
configuration is required; the port simply outputs when written to and inputs when read.
Expansion Digital I/O
The WBK41 has the ability to expand its Digital I/O capabilities via the rear panel P2 port via the
connection of applicable Digital I/O expansion modules, i.e., a DBK20 Series card or module. These
modules are discussed in the DBK
Option Cards & Modules User’s Manual. When using Digital I/O
expansion modules the local P2 Intel 8255 Digital I/O becomes inaccessible in lieu of the expansion
modules. The expansion modules provide additional Intel 8255 ports, as well as input isolation for
applications that require the expanded capabilities.
Pulse Stream Output Using Timers
The WBK41 allows for the generation of output pulses based upon a programmable setting. These output
timers can be set at any time regardless of the state of any synchronous or asynchronous operations which
are currently taking place on other channels. Connections for the two Timer Outputs, designated as
“TMR 0” and “TMR 1,”are located on the front panel terminal blocks.
Counter Input Channels
WBK41 modules have Counter Input capabilities for four channels (CNTR0, CNTR1, CNTR2, and
CNTR3). Connection points are provided on a front panel terminal block. Providing that a counter
channel is not configured for synchronous acquisition, it can be used to read counter input. As in the case
of synchronous operations, the four 16-bit counter input channels can be used individually, or can be
cascaded into two 32-bit counter channels. For either cascaded or non-cascaded counter channels, each
channel can be configured for:
• Clear on Read Mode – specifies that each counter should be reset to zero upon being
read.
• Continuous Totalize Mode – specifies that each counter is to free-run and not be
cleared during the read operation.
pg. 18, WBK40 & WBK41 926896 Thermocouple and Multifunctional Modules