Watlow CAS200 - Manual (Page 36)

Chapter 2: Installation CAS200 User’s Guide
24 Watlow Anafaze
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WARNING! The scanner uses a floating ground system.
Therefore, isolate input devices or host
computers connected through communications
cables (like EIA/TIA-232) from earth ground. Use
ungrounded thermocouples with the
thermocouple sheath electrically connected to
earth ground. Use optically isolated EIA/TIA-232
devices to isolate earth grounded host computers
from the scanners.
When you use grounded thermocouples, tie the
thermocouple sheaths to a common earth ground
in one place. Otherwise any common mode
voltages that exceed 5 volts may cause incorrect
readings or damage to the scanner.
Voltage Input Connections
This input type requires scaling resistors. Special input
resistors installed at Watlow Anafaze divide analog input
voltages such that the scanner sees a -20 to 60mV signal on
the channel.
Figure 2.11 Wiring Voltage Input Connections
Current Input Connections
This input type requires special input resistors. Resistors
installed at Watlow Anafaze for analog current signals are
such that the scanner sees a -10 to 60mV signal across its
inputs for the channel.
Figure 2.12 Wiring Current Input Connections
Do not use the scanner’s power supply to power sensors,
transmitters or output devices.
Com
Device with
Output
Voltage
Ch# IN+
Ch# IN+
Com/Ref Com
Device with
Current
Output