Campbell SDM-CD16AC Specifications download pdf (Page 10)

SDM-CD16AC 16 Channel AC/DC Controller

TABLE 1. Datalogger to SDM-CD16AC Connections

Connection

Order SDM-CD16AC Datalogger Function

First 12 V 12 V on datalogger or Power

external supply

Second Gnd Gnd Common ground

C1 C1 (Control Port 1) Data

C2 C2 (Control Port 2) Clock

C3 C3 (Control Port 3) Enable

If the 21X power supply is used to power the SDM-CD16AC, all low level

analog measurements (thermocouples, pyranometers, thermopiles, etc.) must

be made differentially. This is a result of slight ground potentials created along

the 21X analog terminal strip when the 12 V supply is used to power

peripherals. This limitation reduces the number of available analog input

channels and may mandate an external supply for the SDM-CD16AC.

4. Installation

• The SDM-CD16AC must be installed in an enclosure that provides a

pollution degree 2 environment (normally, only nonconductive pollution.

However, a temporary conductivity caused by condensation may be

expected). All Campbell Scientific enclosures meet this requirement.

• Use copper conductors only.

• Wire Range: 30 − 14 AWG

• Tightening Torque: 5 − 7 in./lb.

• Use minimum 60/75 degree C wire.

• Input power must be connected to a class 2 supply only. All Campbell

Scientific power supplies meet the class 2 supply requirements.

The order in which connections are made is critical.

Always connect 12 V first, followed by ground, then Control

Ports.

For datalogger connections, see Table 1.

Multiple SDM-CD16AC's may be wired in parallel by connecting the

datalogger side of one SDM-CD16AC to the next. For CR10 and 21X

dataloggers, the total length of the cables connecting the SDM-CD16AC's

should not exceed 20 feet.

Total cable lengths in excess of 20 feet will adversely influence

communication performance. For CR7 dataloggers, the total cable length

should not exceed 600 feet.

CAUTION

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Campbell SDM-CD16AC Specifications Page 10