Watlow PPC-2000 - Manual (Page 180)

Chapter 4: Troubleshooting PPC-2000 User’s Guide
154 Watlow Anafaze Doc.# 30002-00 Rev 2.3
Troubleshooting and Corrective Actions
If the system fails to perform as expected, it may be necessary
to perform one or more of the following procedures to discover
the cause and restore normal operation.
Digital Inputs and Outputs
If a digital input or output doesn’t seem to be working, check
the following:
• Is the digital I/O point’s Direction set correctly as an input
or output? See Digital I/O on page 132.
• Is the Logic set correctly? Refer to Digital I/O on page 132.
• Is the output selected as an Output Destination for more
than one function (e.g. a control output and an alarm
output)? See Channels on page 115 and Alarms on page
123.
• Is the digital I/O point associated with a variable set as an
output in a logic program? Refer to the LogicPro User’s
Guide.
• Are the cable and wiring connections correct? See
Connecting I/O to the PPC-2010 on page 37, Connecting to
the Relay Outputs on the PPC-206x on page 70, and
Connecting Digital Inputs to the PPC-207x on page 74.
• Is leakage current from one of the configurable I/O points
such that a device is being switched on or partly on? See
Connecting Digital Outputs on page 41.
• Is the field I/O device powered? Note digital outputs on the
PPC-2010 and PPC-2040 sink current. That current must
be sourced by an external device that is referenced to the
PPC’s common. See Connecting Digital Outputs on page 41
for the PPC-2010 and Connecting Digital Outputs on page
65 for the PPC-2040.
Process Variable
If the Process Variable is not updating, check the following:
• Is a valid analog input selected as the PV Source? See
Channels on page 115.
• Is the input corresponding to the PV Source updating as
expected? If not check LEDs on the associated module, See
corresponding module section in this chapter.
• Is the input wiring correct? See Connecting I/O to the
PPC-2010 on page 37, Connecting Analog Inputs to the
PPC-2021 — 2025 on page 45, Connecting Encoders and
Analog Outputs to the PPC-2030 on page 55, or Connecting
to the Relay Outputs on the PPC-206x on page 70.