Campbell Scientific SDM-CD16D 16-Channel Digital Control Port Expansion Module - Manual (Page 12)

SDM-CD16D 16 Channel Digital Control Port Expansion Module
Instruction 104 – SDM-CD16D used with CR10/10X, CR23X,
CR7and 21X dataloggers
Parameter Type Description
1
2 Reps (No. of modules sequentially addressed)
2 2 Starting Address (base 4: 00..33)
3 4 Starting Input Location
Execution Time = 2 ms per Rep for the CR10/10X and CR23X
3.5 ms per Rep for the 21X and CR7
Instruction 29 – SDM-CD16D used with older CR7s
Parameter Type Description
1
2 Reps (No. of modules sequentially addressed)
2 2 Device (2 = SDM-CD16D)
3 2 Starting Address (base 4: 00..33)
4 2 Card (Excitation card No.)
5 4 Starting Input Location
Execution Time = 150 ms to 190 ms per Rep
The number of SDM-CD16Ds to be addressed is defined by the Reps
(repetitions) parameter. Each Rep sequentially addresses (00, 01, 02,...32, 33)
SDM-CD16Ds, starting with the address specified in parameter 2 (parameter 3
for Instruction 29).
For each repetition, the 16 ports of the addressed SDM-CD16D are set
according to 16 sequential input locations starting at the input location
specified in parameter 3 (parameter 5 for Instruction 29). Any non-zero value
stored in an input location activates (sets HI 5 V) the associated SDM-CD16D
port. A value of zero (0) de-activates the port (sets LO 0 V). For example,
assuming two repetitions and a starting input location of 33, outputs 1 to 16 of
the first SDM-CD16D are set according to input locations 33 to 48, and
outputs 1 to 16 of the second SDM-CD16D are set according to input locations
49 to 64.
For older CR7s with Instruction 29, the Device (parameter 2) specifies what
type of synchronously addressed peripheral is to be addressed. The Device
code for an SDM-CD16D is 2.
For Instruction 29 only (older CR7s), the Card parameter (parameter 4)
specifies which 725 Excitation Card is being used for the control port signals.
The Reps parameter does not advance beyond the specified Card, requiring
another Instruction 29 for each 725 Excitation Card used.
7. Theory of Operation
On power-up, all SDM-CD16D outputs are off /LO.
The SDM-CD16D is a synchronously addressed peripheral. C2 and C3, driven
high by the datalogger, initiate a cycle. While holding C3 high, the datalogger
drives C2 as a clock line and C1 as a serial data line. The datalogger shifts out
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