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Field Wiring 35Chapter 2
Chapter 2
Field Wiring
About This Chapter
This chapter shows how to plan and connect field wiring to the VT1422A's
Terminal Module. The chapter explains proper connection of analog signals
to the VT1422A, both two-wire voltage type and four-wire resistance type
measurements. Connections for other measurement types (e.g. strain using
the Bridge Completion SCPs) refer to the specific SCP manual. Chapter
contents include:
• Planning the Wiring Layout . . . . . . . . . . . . . . . . . . . . . . . . . . page 35
• Faceplate Connector Pin-Signal Lists. . . . . . . . . . . . . . . . . . . page 39
• Optional Terminal and Connector Modules . . . . . . . . . . . . . . page 40
• Reference Temperature Sensing with the VT1422A . . . . . . . page 44
• Preferred Measurement Connections . . . . . . . . . . . . . . . . . . . page 46
• Connecting the On-Board Thermistor. . . . . . . . . . . . . . . . . . . page 49
• Wiring and Attaching the Terminal Module . . . . . . . . . . . . . . page 50
• Removing the VT1422A Terminal Modules. . . . . . . . . . . . . . page 52
• Attaching and Removing the VT1422A RJ-45 Module . . . . . page 53
• Adding Components to the Terminal Module. . . . . . . . . . . . . page 54
• Spring and Screw Terminal Module Wiring Maps . . . . . . . . . page 55
Planning the Wiring Layout
The first point to understand is that the VT1422A makes no assumptions
about the relationship between Signal Conditioning Plug-on (SCP) function
and the position in the VT1422A that it can occupy. Any type of SCP can be
placed into any SCP position. There are, however, some factors which should
be considered when planning what mix of SCPs should be installed in each
of the VT1422As. The following discussions will help explain and clarify
these factors.
SCP Positions and
Channel Numbers
The VT1422A has a fixed relationship between Signal Conditioning Plug-on
positions and the channels they connect to. Each of the eight SCP positions
can connect to eight channels. Figure 2-1 shows the channel number to SCP
relationship.