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PCI-20020M-1 I/O Module Overview

Analog Trigger/Alarm Expansion Module

The PCI-20020M-1 adds analog triggering functions to any expandable Intelligent Instrumentation board. The option module can monitor 1 or 2 analog channels and will generate a digital output when pre-programmed conditions are satisfied. Thresholds in the range of ±10V can be programmed with 8-bit (78mV) resolution. A trigger can be initiated on one of the following conditions: input BELOW limit, input ABOVE limit, input BETWEEN limits, or input OUTSIDE limits.

A pair of D/A converters and comparators perform the above functions. In the window modes (inputs Between or Outside), both comparators are connected to a single input. In all modes of operation the comparator outputs are combined with logic to produce a single output. The module can be programmed to trigger on true or false conditions. To minimize any oscillations or erroneous triggering, the comparators are designed with approximately 25mV of hysteresis. The individual D/A converter and comparator outputs are available for external use.

Jumper options select the mode of operation, gating of the digital output, and whether or not the output is latched. Once latched, the alarm indication will remain until cleared by software.

Use With Other Analog Input Products - The PCI-20020M-1 Trigger/Alarm Module provides two unique functions when used in conjunction with a companion analog input product (PCI-20098C or PCI-20501C-1 boards, PCI-20023M-1 or PCI-20341M-1 Modules):

It establishes a trigger on a given analog signal level and slope.
It ensures reliable analog triggering at high speeds by eliminating the possibility of channel rotation.

Channel rotation refers to the situation in which the indicated channel at the input multiplexer is out of step with the recorded data (for example: the data for channels 2, 3, 4, 5, ... is reported as corresponding to channels 3, 4, 5, 6, ...). This condition occurs when the input multiplexer receives a pacing signal from the timebase generator or external source (telling it to advance to the next channel) before the system initializes and is ready to begin the A/D conversion. By gating the pacing signal through the Trigger/Alarm Module, the correct timing conditions can be ensured.

Features & Benefits

• Ensures Reliable Triggering

• Speeds Triggers On High, Low, or Window Comparisons

• Software Programmable Thresholds

• 3.5µsec Response Time (Maximum)

Hardware Specifications

Parameter	Conditions	Specifications

Trigger Inputs
Number of Channels	Level compare	2
	Window compare	1
Sync output*		Follow/latched, gated sync in
Comparators
Number		2
Input Range	Linear	±10V
Overvoltage Protection	Power On	±15V
Offset Voltage	Maximum	±7.5V
Bias Current		300nA
Hystersesis		25mV
References
Number	D/A converters	2
Resolution		8 bits
Step Size	Minimum increment	78.1mV
Range		-10V to 9.92V
Linearity		±1/2LSB
Response Time
	Input to sync output, maximum	3.5us
Physical Characteristics
Power Requirements**	+5V	265mA maximum
	+15V	35mA maximum
	-15V	25mA maximum
Operating Temperature Range		0 to 70° C
* When the system is first powered up, the outputs of this module are NOT in determined states until initialized by software. Therefore the analog outputs could be any value between ±10V, and the digital outputs could be either "high" or "low".
** Refer to the data sheet of the host board to determine available power.