BayTech V79 PDI-1 User manual

OWNER'S MANUAL
________________
MODEL V79 PDI-1 AND V80 PDI-2
SWITCH INPUT AND OPTICALLY
ISOLATED INPUT MODULES
BayTech Publication #U140E105

Thank you for selecting a BayTech Model V79 PDI-1 Switch Input Module or
Model V80 PDI-2 Optically Isolated Input Module.
The data provided in this Owner's Manual explains the various ways you can
operate the V79 PDI-1 or V80 PDI-2, and how to configure your unit. We
suggest that you read this manual carefully before attempting to install a PDI, and
that you place special emphasis on correct cabling and configuration. If you have
any problems with your installation, please contact a BayTech applications
engineer for assistance.
BayTech also manufactures other data communications devices that provide port
sharing and expansion, networking, port contention, buffered and non-buffered
printer sharing, network print servers, and statistical multiplexing. If you would
like information on any of these models, please contact BayTech Customer
Service.
We welcome any comments you may have about our products. And we hope that
you will continue to look to BayTech for your data collection and communications
needs.
NOTE: The information contained in this document is subject to change without
notice.
Copyright 1994 by Bay Technical Associates, Inc.
IBM, IBM PC, IBM PC/AT, IBM PC/XT are products and registered trademarks
of International Business Machines Corporation.
Hewlett-Packard LaserJet and Draftmaster I Plotter are products and registered
trademarks of the Hewlett-Packard Company.

TABLE OF CONTENTS
1GENERAL............................................................................................................................................................................................ 1
1.1 V79 PDI-1 MODULE.................................................................................................................................................. 2
1.2 V80 PDI-2 MODULE.................................................................................................................................................. 2
2SPECIFICATIONS............................................................................................................................................................................... 3
2.1 V79 PDI-1 SWITCH INPUT STATUS MODULE.................................................................................................... 3
2.2 V80 PDI-2 OPTICALLY ISOLATED INPUT MODULE....................................................................................... 4
3INSTALLATION................................................................................................................................................................................. 5
3.1 CABLING..................................................................................................................................................................... 5
3.2 PDI-2 AC INPUT SETUP........................................................................................................................................... 6
4OPERATION....................................................................................................................................................................................... 7
4.1 GENERAL.................................................................................................................................................................... 7
4.2 USER-PROGRAMMABLE FEATURES.................................................................................................................... 8
4.2.1 SAMPLING SETUP............................................................................................................................ 8
4.2.2 REPORTING SETUP.......................................................................................................................... 8
4.2.2.1 REPORTING METHOD............................................................................................. 8
4.2.2.2 REPORT START TIME............................................................................................... 9
4.2.2.3 REPORT INTERVAL.................................................................................................. 9
4.2.2.4 HOST ADDRESS......................................................................................................... 9
4.2.2.5 TIME TAG................................................................................................................... 9
4.2.2.6 TERMINATING CHARACTER(S) .......................................................................... 10
4.2.3 DYNAMIC CONFIGURATION....................................................................................................... 10
4.3 DATA COMMANDS................................................................................................................................................. 10
4.3.1 CLEAR EVENT BUFFER COMMAND........................................................................................... 12
4.3.2 CLEAR EVENT COUNTER COMMAND....................................................................................... 12
4.3.3 CLEAR EVENT LATCH DATA...................................................................................................... 12
4.3.4 REPORT ALL BUFFERED EVENTS COMMAND........................................................................ 13
4.3.5 REPORT EVENT COUNTER COMMAND.................................................................................... 13
4.3.6 REPORT EVENT DURATION COMMAND.................................................................................. 13
4.3.7 REPORT EVENT LATCH DATA COMMAND............................................................................. 14
4.3.8 REPORT EVENT COUNTER AND RESET COMMAND............................................................. 14
4.3.9 REPORT EVENT LATCH DATA AND RESET COMMAND...................................................... 14
4.3.10 REPORT A SINGLE BUFFERED EVENT COMMAND................................................................ 15
4.4 EVENT SAMPLE REPORTING.............................................................................................................................. 15
4.5 EVENT SAMPLE PRESENTATION....................................................................................................................... 17

5CONFIGURATION........................................................................................................................................................................... 19
5.1 MENU-DRIVEN CONFIGURATION..................................................................................................................... 19
5.1.1 CONFIGURATION MAIN MENU.................................................................................................. 21
5.1.2 MODULE STATUS........................................................................................................................... 22
5.1.3 SAMPLING SETUP.......................................................................................................................... 22
5.1.4 REPORTING SETUP........................................................................................................................ 23
5.1.4.1 REPORTING METHOD........................................................................................... 24
5.1.4.2 REPORT START TIME............................................................................................. 25
5.1.4.3 REPORT INTERVAL................................................................................................ 26
5.1.4.4 HOST ADDRESS....................................................................................................... 27
5.1.4.5 TIME TAG................................................................................................................. 27
5.1.4.6 TERMINATING CHARACTER(S) .......................................................................... 28
5.1.5 DYNAMIC CONFIGURATION....................................................................................................... 28
5.1.6 EXIT................................................................................................................................................... 29
5.2 DYNAMIC CONFIGURATION PROCEDURE AND COMMANDS................................................................... 30
5.2.1 DEBOUNCE DELAY COMMAND................................................................................................. 31
5.2.2 REPORTING METHOD COMMAND............................................................................................. 31
5.2.3 TIME TAG COMMAND................................................................................................................... 31
5.3 FRONT PANEL CONFIGURATION....................................................................................................................... 32
APPENDIX A
DATA/CONFIGURATION COMMAND SUMMARY........................................................................................................................................... 33
APPENDIX B
EPROM UPGRADE.................................................................................................................................................................................................. 34
APPENDIX C
V79 PDI-1 MECHANICAL LAYOUT.................................................................................................................................................................... 35
APPENDIX D
V80 PDI-2 MECHANICAL LAYOUT.................................................................................................................................................................... 36
APPENDIX E
INDEX........................................................................................................................................................................................................................ 37

1
1GENERAL
BayTech's PDI modules are designed for use with the M16 and M8 (DAC) Data
Acquisition Controllers. Both modules are used to detect events where an event is
defined as a change-in-state of an input and return to the original state. The V79
PDI-1 module is used for the detection of switch closure in applications requiring
notification of device status such as burglar alarms, fire alarms, event counters
and timers, process control, etc.. The V80 PDI-2 is used for the detection of
optically isolated voltage inputs in applications requiring industrial control of
motors, process monitoring, limit switch status, and the monitoring of relay status.
All events detected by either module are recorded as an event sample and sent to a
host computer/controller connected to a V71 host module. The current status of
input channels may be provided to the host computer/controller upon request.
Event samples or input channel status may be provided with a "time stamp" or
"Time Tag" which is available through the use of a "time-of-day" clock located in
the M16/M8 base unit. A time tag includes the month, day, year, hour, minute and
second the event occurred or the input channel status was taken.
Event status is supplied to the host computer/controller in one of the following
modes:
1) Upon user request (COMMAND).
2) At a specific date/time (SCHEDULE).
3) Real time reporting of events (i.e., as events occur IMMEDIATE).

2
1.1 V79 PDI-1 MODULE
The main features of the V79 PDI-1 module are sixteen microprocessor-controlled
input channels that can be connected with individual ground returns, or a common
single-point ground. The input channels provide a flexible, reliable method to detect
and report the change-in-state of a circuit. The change can be from infinite
resistance (open) to continuity (closed), and vice versa. For example, the change-
in-state could be for a set of form C (dry) relays or switch contacts. Any change
in the status of individual or multiple inputs may be observed, recorded, reported,
analyzed, and acted upon. The level and type of actions desired or required are
easily selectable through the PDI-1's configuration menu.
Individual or multiple inputs may be polled for present status or configured to
automatically provide an alert message when a change-in-state is observed.
Momentary changes in an input's condition can be monitored and "latched" into
memory for post-action analysis. The reporting of false, or transient events can
be prevented by selection of programmable "debounce times". Input connections
to the PDI-1 are made through a standard DC-37F connector.
1.2 V80 PDI-2 MODULE
The primary feature of the PDI-2 series is sixteen microprocessor controlled,
optically isolated voltage inputs. The PDI-2A is designed for an input "on" voltage
range of 5 to 24 AC or DC volts and the PDI-2B for 100 to 130 AC or DC volts.
All inputs have 500V AC or DC electrical isolation from ground. Inputs are not
polarity sensitive. Therefore, paired signal inputs can be made using the "return"
or "input" terminal as the positive connection.
A mixture of AC and DC inputs can be selected by individual channels. For
example, Channel 1 could be a DC input, Channels 2 and 3 AC inputs, Channel 4 a
DC input, etc.. Dip switches are provided for selection of low-pass filtering
during AC input operation.

3
These optically isolated inputs provide an efficient means for the monitoring of
external process and control functions. All functions provided by the board are
programmable through a series of detailed configuration menus. Additional
functionality is made available through the use of BayTech or user provided
application software. Input connections to the PDI-2 are made through a standard
DC-37F connector.
2SPECIFICATIONS
2.1 V79 PDI-1 SWITCH INPUT STATUS MODULE
(typical for 25oC unless otherwise noted)
INPUTS: 16 with individual ground returns or common (single-point)
ground.
DRIVE DISTANCE: Up to 1000 Ohms cable resistance, for
example: AWG 36 - 2400 ft., AWG 24 - 15000 ft., AWG 22 -
62000 ft.
POWER REQUIREMENTS: +5VDC, 40 ma typical (provided by
M16/M8 pwr supply).
DEBOUNCE: 0 to 60000 ms (software selectable).
ENVIRONMENTAL:
Operating temperature range: 0oto 70o C
Storage temperature range: -40oto 85oC
Humidity: 5% to 95% non-condensing

4
2.2 V80 PDI-2 OPTICALLY ISOLATED INPUT MODULE
MODULE TYPE PDI-2A PDI-2B
NUMBER OF INPUTS:16 16
INPUT VOLTAGE RANGE: 5-24 100-130 AC/DC
MAXIMUM INPUT CURRENT: 50ma 20ma
MINIMUM TURN ON CURRENT:8ma 8ma
MAX TURN ON TIME: 1ms 1ms
MAX TURN OFF TIME: 1ms 1ms
VOLTAGE ISOLATION: 500V500V
(Input to Input and Input to ground)
POWER REQUIREMENTS: +5VDC, 40 ma typical (provided by
M16/M8 pwr supply)
DEBOUNCE TIME: 0 to 60000 ms (software selectable)
ENVIRONMENTAL:
Operating temperature range: 0oto 70o C
Storage temperature range: -40oto 85oC
Humidity: 5% to 95% non-condensing

5
3INSTALLATION
The PDI-1 and PDI-2 are installed in the M Series chassis as described in Section
3.5 of the base unit operator's manual.
NOTE: The PDI-1 or PDI-2 cannot be installed as Module 1. If an PDI-1 or PDI-
2 is removed from a module slot and a different PDI-1 or PDI-2 is installed in that
location, the newly installed module acquires the previous module's configuration.
Moving an PDI-1 or PDI-2 to a different module location requires reconfiguration
because the configuration parameters are stored as a function of slot location and
module type. The configuration information does not stay with a relocated
module.
3.1 CABLING
The V79 PDI-1 and V80 PDI-2 modules each have a DC-37F connector.
Equipment connections for each module is similar. Each input of the V79 module
has a ground connection and each input of the V80 module has a return
connection. Figure 1 and Figure 2 below show the V79 and V80 connections
respectively.
Circuit Pin # Circuit Circuit Pin # Circuit
Connection Connection Connection Connection
 
Input #1 1 20Ground #10 Input #1 1 20Return #10
Ground #1 2 21Input #11 Return #1 2 21Input #11
Input #2 3 22Ground #11 Input #2 3 22Return #11
Ground #2 4 23Input #12 Return #2 4 23Input #12
Input #3 5 24Ground #12 Input #3 5 24Return #12
Ground #3 6 25Input #13 Return #3 6 25Input #13
Input #4 7 26Ground #13 Input #4 7 26Return #13
Ground #4 8 27Input #14 Return #4 8 27Input #14
Input #5 9 28Ground #14 Input #5 9 28Return #14
Ground #5 10 29Input #15 Return #5 10 29Input #15
Input #6 11 30Ground #15 Input #6 11 30Return #15
Ground #6 12 31Input #16 Return #6 12 31Input #16
Input #7 13 32Ground #16 Input #7 13 32Return #16
Ground #7 14 33N.C. Return #7 14 33N.C.
Input #8 15 34N.C. Input #8 15 34N.C.
Ground #8 16 35N.C. Return #8 16 35N.C.
Input #9 17 36N.C. Input #9 17 36N.C.
Ground #9 18 37N.C. Return #9 18 37N.C.
Input #10 19 Input #10 19 
 
Figure 1: V79 Input Connections: V79 Input Connections Figure 2: V80 Input Connections: V80 Input Connections

6
3.2 PDI-2 AC INPUT SETUP
The PDI-2 module has two banks of dip switches which are used to add ripple
filtering for AC inputs. AC input is selected by individual channel. Location of the
dip switches is shown in Figure 3.
CHANNEL SW1 SW2
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 1
10 2
11 3
12 4
13 5
14 6
15 7
16 8
Table 1
Dip switch SW1 1-8 provides filtering control for channels 1-8 while SW2 1-8
controls channels 9-16. Refer to Table 1 to determine which switch corresponds
to a particular channel. A port is configured for AC operation by positioning the
corresponding switch to ON position.
NOTE: The default setting for SW 1-8 and SW2 1-8 is "OFF" (AC filtering
disabled).
Figure 3

7
4OPERATION
This section discusses the general PDI operation (Section 4.1), user-programmable
features (Section 4.2), data commands (Section 4.3), event sample reporting
(Section 4.4), and presentation (Section 4.5).
4.1 GENERAL
The V79 PDI-1 and V80 PDI-2 modules are used in applications requiring
notification of device status (e.g., burglar and fire alarms, event counters/timers,
process control, etc.). The PDI-1 module has 16 channel switch inputs providing
a reliable method to detect and report a state change from high resistance (open) to
continuity (closed) or vice versa. The V80 is a 16 channel optically-isolated
voltage input module that is non-polarity sensitive and can be individually set to
detect the presence or the change of state of AC or DC inputs. We will refer to a
change in state of a switch closure (PDI-1) or a voltage change (PDI-2) as an
event. An event sample is the actual data associated with an event which is
calculated by the PDI module and sent to the host computer/controller.
Individual PDI channels can be programmed to report event samples upon request
via data commands (Command Reporting Method), at a specific date/time
(Schedule Reporting Method), or as the event occurs (Immediate Reporting
Method). Multiple events may be stored for later retrieval and analysis. The PDI
features a latch mode where the time and state of the initial event is latched and
held until user reset. False reporting of events is prevented by programming
variable debounce times. Event samples are preceded by the appropriate unit,
module, and channel number and may be appended with a "real time" Time Tag
showing the date and time the status was recorded.
You have the choice of programming the PDI via verbose (menu-driven) or non-
verbose (dynamic) configuration mode. When using verbose mode, a series of
menus will prompt you to enter the desired parameters. Non-verbose mode allows
you to program the PDI by downloading configuration commands (see Section
5.2).

8
4.2 USER-PROGRAMMABLE FEATURES
You may program the Sampling Setup, Reporting Setup, and Dynamic
Configuration on the PDI which are discussed in Section 4.2.1 through Section
4.2.3 respectively.
4.2.1 SAMPLING SETUP
Sampling Setup allows you to program the Debounce Delay and Latch Polarity for
the input channels. The Debounce Delay is used to guard against erroneous
events. An event will not be valid unless the input channel has remained at a
changed state for the debounce duration. The debounce delay may be
programmed from 0 (for no debounce) to 65535 milliseconds. The Latch Polarity
is used to latch individual inputs based on a positive going (LO to HI) or negative
going (HI to LO) input. The latch information is retained in memory until recalled
by the user. The default Debounce Delay time is 100 milliseconds and the default
Latch Polarity is a HI to LO transition.
4.2.2 REPORTING SETUP
Reporting Setup allows you to program how the PDI reports event samples to the
host module. The items you may program in the Reporting Setup include
Reporting Method, Report Start Time, Report Interval, Set Host Address, Data
Format, Time Tag, and Terminating Character(s). The following subsections
describe these features in more detail.
4.2.2.1 REPORTING METHOD
Reporting Method is the manner in which event samples are sent to the designated
host module. The PDI provides three Reporting Methods: Command (upon
request via data commands), Immediate (upon exiting configuration), and
Schedule (where reporting begins at a specified time). The default Reporting
Method is Command.

9
4.2.2.2 REPORT START TIME
Report Start Time is the time reporting begins when Schedule Reporting Method is
selected. The start of reporting may be delayed up to 24 hours from the current
time recorded by the M Series time-of-day clock and reporting will occur in cyclic
periods as determined by the Report Interval. The default Report Start Time is
00:00.
4.2.2.3 REPORT INTERVAL
You may program the PDI to report in repetitive periods using Schedule Reporting
Method, where the PDI will report all event samples in the receive buffer after the
specified Report Interval has elapsed. The PDI will report until the buffer is empty
and then report again after the specified Report Interval has expired. The default
Report Interval is 00:00 (every 24 hours).
4.2.2.4 HOST ADDRESS
Host Address is the designated host module where event samples are sent when
using Immediate or Schedule Reporting Method. The Host Address consists of
the Unit Number (1 to 32), Module Number (1 to 16), and Port Number (1 to 4)
of the designated host module. The default Host Address is Unit 1, Module 1, Port 1.
4.2.2.5 TIME TAG
When Time Tag is enabled, a time tag is appended immediately after the event
sample. The time tag consists of the month, day, year, hour, minute, and second
at which the data was calculated. Time Tag may be enabled or disabled. The
default Time Tag is disabled.

10
4.2.2.6 TERMINATING CHARACTER(S)
The Terminating Character(s) is added at the end of an event sample to match the
requirements of the host terminal or application software. The Terminating
Character(s) consists of one or two hexadecimal characters. The default
Terminating Characters are 0D Hex (Carriage Return) followed by 0A Hex (Line
Feed).
4.2.3 DYNAMIC CONFIGURATION
You may enable or disable Dynamic Configuration for the PDI. Dynamic
configuration mode allows non-verbose or "on-the-fly" configuration commands to
be issued to the PDI which are summarized in Section 5.2. The default Dynamic
Configuration setting is disabled.
4.3 DATA COMMANDS
You may issue PDI data commands through a host module to perform single
operations while temporarily overriding the module's current operating
configuration. Some data commands apply to all types of DAC modules, while
others apply to specific modules. Data commands may be entered repeatedly to
get specific event samples. You may issue a single data command to obtain event
samples from multiple channels. Data commands must be used to obtain event
samples when using Command Reporting Method.
PDI data commands are sent through a host module using the following
procedure:
1. Select the PDI from the host module by sending a select sequence which
consists of the port select code ($BT - default), the desired module
number (2 to 16), and a terminating character of Carriage Return (0D
Hex) or Line Feed (0A Hex). For example, to select an PDI Module
located in slot 15 using the default port select code, send $BT15<cr>.

11
2. Once the PDI is selected, it will go into Command Mode and allow you to
send data commands. The PDI data commands begin with two capital
letters designating the specific command and are terminated with a
Carriage Return. Most data commands also require a number between
the command letters and Carriage Return. This number is typically the
desired channel(s) for the data command. If you have a requirement to
send the data command to multiple channels simultaneously, you may use
one of the following formats as shown for the SA (sample) command:
SA1,2,3,4,5,6,7,8<cr> Take a single sample for Ports 1-8
SA1-8<cr> Take a single sample for Ports 1-8
SA/0<cr> Take a single sample for Ports 1-8
SA1,2,4-8<cr> Take a single sample for Ports 1, 3, 4, 5, 6, 7,
and 8
3. After you have sent the desired data commands to the PDI module, you
may disconnect from the PDI by sending $BT<cr>. You may disconnect
from the PDI and select a different module or the base unit by sending
$BTX<cr>, where X is the desired module number or 0 for the base unit.
IMPORTANT: If the PDI is operating in self reporting mode (i.e.,
Immediate or Schedule Reporting Method) and a host device issues a data
command, the host device must disconnect by sending the Port Select
Code and Carriage Return or Line Feed before the PDI will resume
sending event samples to the designated host module.
Section 4.3.1 through Section 4.3.10 provide detailed information on the
functionality of each data command supported by the PDI. Appendix A provides
these same commands in a condensed version for quick reference.

12
4.3.1 CLEAR EVENT BUFFER COMMAND
The Clear Event Buffer (CB) command is used to clear all stored event samples
from the buffer of the selected channel(s). The Clear Event Buffer command has
the following format:
CBn<cr>
where c= Channel# (1 to 16 or 0 for all).
4.3.2 CLEAR EVENT COUNTER COMMAND
The Clear Event Counter (CC) command is used to reset the event counter for one
or more channels to zero without reading the value of the event counter. The
function of the event counters is discussed in Section 4.4. The Clear Event
Counter command has the following format:
CCc<cr>
where c= Channel# (1 to 16 or 0 for all).
4.3.3 CLEAR EVENT LATCH DATA
The Clear Event Counter (CR) command is used to clear the event latch buffer.
Latched data is discussed more in Section 4.4. The Clear Event Counter command
has the following format:
CRc<cr>
where c= Channel# (1 to 16 or 0 for all).

13
4.3.4 REPORT ALL BUFFERED EVENTS COMMAND
The Report All Buffered Events (RA) command instructs the PDI to report all
event samples currently stored in the buffer of the selected channel(s). The
Report All Buffered Events command has the following format:
RAn<cr>
where c= Channel# (1 to 16 or 0 for all).
4.3.5 REPORT EVENT COUNTER COMMAND
The Report Event Counter (RC) command instructs the PDI to report how many
times an event has occurred for one or more channels since the last time a counter
reset command was issued. This command does not reset the event counter.
The Report Event Counter command has the following format:
RCc<cr>
where c= Channel# (1 to 16 or 0 for all).
4.3.6 REPORT EVENT DURATION COMMAND
The Report Event Duration (RD) command instructs the PDI to report how long
the most recent recorded event for the selected channel(s) lasted. Event duration
is discussed more in Section 4.4. The Report Event Duration command has the
following format:
RDc<cr>
where c= Channel# (1 to 16 or 0 for all).

14
4.3.7 REPORT EVENT LATCH DATA COMMAND
The Report Event Latch Data (RL) command instructs the PDI to report the active
state of the initial event and the time the initial event occurred (if time tagging is
enabled). This command does not reset the latch buffer. The Report Event Latch
Data has the following format:
RLc<cr>
where c = Channel# (1 to 16 or 0 for all).
4.3.8 REPORT EVENT COUNTER AND RESET COMMAND
The Report Event Counter and Reset (RO) command instructs the PDI to report
how many times an event has occurred for one or more channels and then reset
the event counter to zero. The Report Event Counter and Reset command has the
following format:
ROc<cr>
where c= Channel# (1 to 16 or 0 for all).
4.3.9 REPORT EVENT LATCH DATA AND RESET COMMAND
The Report Event Latch Data and Reset (RR) command instructs the PDI to
report the active state of the initial event, the time the initial event occurred (if time
tagging is enabled), and then reset the latch buffer. The Report Event Latch Data
and Reset command has the following format:
RRc<cr>
where c= Channel# (1 to 16 or 0 for all).

15
4.3.10 REPORT A SINGLE BUFFERED EVENT COMMAND
The Report A Single Buffered Event (RS) command instructs the PDI to report the
first event sample stored in the buffer of the selected channel(s). The Report A
Single Buffer Sample command has the following format:
RSc<cr>
where c= Channel# (1 to 16 or 0 for all).
4.4 EVENT SAMPLE REPORTING
An event is defined as a change-in-state of an input channel and return to the
original state. An event may be started on a rising edge (LO to HI) or a falling
edge (HI to LO) as determined by the Latch Polarity (see Section 5.1.3). On the
PDI-1 switch closure module, an input is considered to be at a "HI" or "1" state
when it is closed (continuity) and a "LO" or "0" state when it is open (infinite
resistance). On the PDI-2A and PDI-2B optically isolated modules, an input is
considered to be at a "HI" or "1" state when there is voltage detected and a "LO" or
"0" state whenever there is no voltage detected. An event sample is the actual data
associated with an event which is calculated by the PDI module and sent to the
host computer/controller. The way an event sample is presented to the host
computer/controller is described in Section 4.5.
PDI event sample reporting depends on the Reporting Method used. When using
Immediate Reporting Method, the PDI will report an event sample whenever an
event occurs. When using Schedule Reporting Method, the PDI will report an
event sample whenever a event occurs after the Report Start Time has elapsed
(see Section 4.2.2.2). When using Command Reporting Method, the PDI will
report an event sample or multiple samples on command only.

16
The PDI module can observe, record, and report when an event happened, how
long the event lasted, and how many events occurred for each individual channel.
The initial occurrence of an event will set the event latch bit and store the
associated time in the latch buffer. You may read the state of the initial event and
the time it was recorded (if time tagging is enabled) by issuing the RL or RR
commands.
Each occurrence of an event starts the duration counter and increments the event
counter. The duration counter measures event duration time in milliseconds with a
maximum time of 65,535 stored. You may read the duration of the last recorded
event by issuing the RD command.
NOTE: Duration measurements are not de-bounced. If the input circuit cycles
between active and inactive before settling, only the settled value is reported.
Therefore, if a PDI module is connected to a relay or switch that has "dirty"
contacts, the total measurement will be less than the actual activation duration of
the circuit by the amount of time spent settling.
The event counter reflects the total number of events that have occurred since the
event counter was last cleared using the CC or RO command. You may read the
current event counter value by sending the RC or RO command. The event
counter will trigger on the rising edge of an event when LO to HI Latch Polarity is
selected or on the falling edge of an event when HI to LO Latch Polarity is
selected. Examples of using the event counter would include counting items
moving on a conveyor belt and process control where a pre-determined number of
events must take place before a defined action may take place.
NOTE: An event must have a duration greater than one millisecond plus the
current debounce delay time to increment the event counter.