Campbell Scientific CR7 Measurement and Control System - Manual (Page 155)

SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
15-5
TABLE 15.2-2. Hardware Components in SC94
Component Description
Interconnect Cable (1 ea.) Length of the 4-wire cable is made to order, circular connectors
attached at both ends.
Mating Circular Connector (2 ea.) One connector affixed to Control Module enclosure; other
connector affixed to remote I/O Module enclosure; each joined
to a SC94 circuit card.
SC94 Circuit Card (2 ea.) One card fastens to the remote I/O Module enclosure, the other
to the Control Module enclosure; both have circular socket
connectors.
10-Conductor Ribbon Cable Ribbon cable connects SC94 circuit card to Control Module's
Serial Interface cord or to remote I/O Module's Controller card.
Grounding Wire (2 ea.) 12 AWG; wires are routed between terminals located on SC94
cards and 1 of 3 available terminals on the grounding bar on
left side of I/O Module framework; provides transient protection
at both ends of Interconnect cable.
Mating connectors and the associated circuitry
are installed at the factory when the CR7
System and multiple I/O Modules are purchased
together. An SC94 Four Wire Current Loop
Interconnect assembly is required for each
remote I/O Module operating in a CR7 System.
Table 15.2-2 describes the SC94 hardware.
Remote I/O Modules require their own power
supply. When remote I/O Modules are ordered
with either the Model ENC-7F or the Model
ENC-7L enclosure option, the space normally
taken up by the Control Module can be used for
housing the PS12-LA Power Supply. The
PS12-LA 12V charging regulator and battery
may also be mounted with a remote I/O Module
inside a NEMA type enclosure. Multiple I/O
Modules can be powered by a single Power
Supply if the distance is not too great.
Once all grounding leads are in place the power
supply leads are usually connected to the
terminal block located on the top left of the I/O
Module's Controller card. Alternatively, the two
power leads can be routed to the terminals,
marked +12V and, ground positioned on the
SC94 card.
NOTE: Whenever power is connected to
the I/O Module, it draws current even when
the power switch on the Control Module is
in the OFF position.
15.2.1 PROGRAMMING CONSIDERATIONS
The mating connector(s) affixed to CR7
Systems configured to operate with multiple I/O
Modules are labeled with a unique I/O Module
identification number (e.g., 1, 2, 3, 4) before
they leave the Factory. Instruction 23 is used to
address subsequent programming instructions
to a particular I/O Module.
At the start of each Program Table, the Control
Module assumes all instructions are meant for
I/O Module #1, the I/O Module housed with the
Control Module. Instruction 23 must be used to
address instructions to I/O Modules other than
#1. Once Instruction 23 is executed,
subsequent instructions are addressed to the
specified I/O Module until Instruction 23 is
executed again or the I/O Module again defaults
to #1 at the start of a Program Table.