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Campbell Scientific CR7 Measurement and Control System User Manual

Page 100

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SECTION 9. INPUT/OUTPUT INSTRUCTIONS

9-10

instructions and examples. This instruction is
not in all PROM options.

PARAM.

DATA

NUMBER

TYPE

DESCRIPTION

01:

2

SDM address (base

4:00..33)

02:

4

*Input configuration;

channels 8,7,6,5

03:

4

*Input configuration;

channels 4,3,2,1

04:

4

**Function; channels 8,7,6,5

05:

4

**Function; channels 4,3,2,1

06:

4

***Output option

07:

4

Starting input location

number

08:

FP

Mult

09:

FP

Offset

*

Input configurations:

0 = high level, rising edge
1 = high level, falling edge
2 = low level, rising edge
3 = low level, falling edge

** Functions:

0 = no value returned
1 = period in ms
2 = frequency in kHz
3 = time since previous channel's edge

in ms

4 = time since channel 1 in ms
5 = counts on channel 2 since channel

1, linear interpolation

6 = frequency in kHz (low resolution)
7 = counts
8 = counts on Channel 2 since Channel

1, no interpolation

*** Output option:

0

Average over execution interval

0--

Continuous averaging

XXXX

Averaging interval in msec,
XXXX>0

XXXX-- Capture all events until

XXXX edges of channel 1
(0

9999--

Test memory

Input locations altered: 1 per function

*** 102 SDM-SW8A ***

The 8 channel SDM-SW8A Switch Closure Input
Module is a peripheral for measuring up to 8
channels of switch closure or voltage pulse
inputs. Each channel may be configured to read
single-pole double-throw (SPDT) switch closure,
or single-pole single-throw (SPST) switch
closure, or voltage pulse. Output options
include counts, duty cycle, and state. This
instruction is not in all PROM options.

The SW8A is addressed by the datalogger,
allowing multiple SW8A's to be connected to one
datalogger. 16 addresses are available.

If more channels are requested than exist in one
module, the datalogger automatically increments
the address and continues to the next SW8A.
The address settings for multiple SW8A's must
sequentially increase. For example, assume 2
SW8A's addressed as 22 and 23 are connected,
and 12 Reps are requested. 8 channels from
the first SW8A and the first 4 channels from the
next will be read.

Only one Function Option (Parameter 3) may be
specified per Instruction 102. If all 4 functions are
desired, the instruction must be entered 4 times.

Function Option 0 provides the state of the
signal at the time P102 is executed. A 1 or
0 corresponds to high or low states,
respectively.

Function Option 1 provides signal duty
cycle. The result is the percentage of time
the signal is high during the sample interval.

Function Option 2 provides a count of the
number of positive transitions of the signal.

Function Option 3 provides the signature of
the SW8A PROM. A positive number
(signature) indicates the PROM and RAM
are good, a zero (0) indicates bad PROM,
and a negative number indicates bad RAM.
Function Option 3 is not used routinely, but
is helpful in "debugging". Only one Rep is
required for Option 3.

Parameter 4 specifies the first SW8A channel to
be read (1..8). One or more sequential channels
are read depending on the Reps. To optimize
program efficiency, the sensors should be wired
sequentially.