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SDM-CD16
Control Port Expansion Module with Drivers
2
2
2
4
z
.+
Parameter
1
IBe
2
The number of SDM-CD16s
to
be
addressed
is
defined
by
the Reps (repetitions) parameter.
Each
Rep
will sequentially
address
(00,
01,
02,...32,33) SDM-CD16s starting with the
address specified in parameter
2 (lnstruction
29
parameter
3).
For each
Rep,
the
16
ports
of
the addressed
SDM-CD16 are
set
according
to
16
sequential
Input Locations starting
at
the Input Location
specified in parameter
3 (lnstruction
29
parameter
5).
Any non-zero value stored
in an
Input Location activates (connects
to ground) the
associated SDM-CD16
port.
A
value
of
zero
(0)
de-activates
the port (open
circuit).
For example,
assuming 2
Reps
and
a
starting
lnput Location of
33,
OUTPUT
1
through
16 of
the first SDM-CDI
6
are
set
according
to
Input Locations
33
through
48,
and OUTPUT
1
through
16
ofthe
second
SDM-CD16 are set
according
to
Input Locations
49
through
64.
For Instruction 29
,
the Device (parameter
2)
specifies what
type of synchronously addressed
peripheral
is
to
be
addressed. The Device code
for an SDM-CD16
is
2.
For Instruction 29
only
(CR7),
the Card
parameter 4 specifies
which 725 Excitation Card
is
being used for
the Control Port signals. The
Reps
parameler
does not advance beyond the
specified Card, requiring
another Instruction
29
for each 725 Excitation Card
used.
Instruction
29
- SDM-CD16 use
with
CR7
Description
Reps
(#
of modules
sequentially
addressed)
Device
(2
=
SDM-CD16)
Starting Address
(base
4:
00..33)
Card
Starting Input Location
Execution
Time
=
150
to
190
ms per Rep
7, THEORY OF
OPERATION
The SDM-CD16
is
a
synchronously
peripheral.
C2
and
C3,
driven high by
the
datalogger, initiate
a
cycle.
While
holding
C3
high, the datalogger drives
C2
as
a
clock line
Cl
as a serial
data
line.
The
datalogger shifts
a
data bit on C1
(LSB
first)
on
the
falling edge
the
C2
clock.
The SDM-CD16 shifts
in
the
C1
data bit
on
the rising edge
of
the C2 clock.
The
first 8 bits
clocked out represent the
SDM
CD16
address.
lf
the address matches the
CD16's
jumpered address, the SDM-CDI6
is
enabled. lf enabled, the
ne)ft 16
bits are
into
the SDM-CD16, each bit controlling one
the first
of
which controls OUTPUTl.
When
the
16
control bits are clocked in,
C2
is
held high while C3
is
pulsed low
then high
to
latch the
control
bits.
The datalogger then
lowers both
C3
and
C2
to complete the cycle.
PROGRAM EXAMPLE
The example
is
written for
the
CR10
Measurement and
Control Module. The
concepts presented
are
the same for the
21X
CR7
dataloggers
with minor changes
in
the
program code.
In
this example, the SDM-CD16 is used
to
the
temperature between
23
and
28 oC in
5
greenhouses.
In
each green
housethe
S
CD16
controls a heating unit,
a
refrigerating
and an air mixing fan
according to the
conditions.
8.
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