Watlow CPC400 - Manual (Page 166)

Chapter 6: Troubleshooting and Reconfiguring CPC400 Series User’s Guide
152 Watlow Anafaze Doc. 0600-2900-2000
Additional Troubleshooting for Computer Super-
vised Systems
These four elements must work properly in a computer-su-
pervised system:
• The controller
• The computer and its EIA/TIA-232 or EIA/TIA-485 se-
rial interface
• The EIA/TIA-232 or EIA/TIA-485 communication
lines
• The computer software
For troubleshooting, disconnect the communications line
from the computer and follow the troubleshooting steps in
the first section of this chapter. The next few sections ex-
plain troubleshooting for the other elements of computer
supervised systems.
Computer Problems
If you are having computer or serial interface problems,
check the following:
• Check your software manual and make sure your com-
puter meets the software and system requirements.
• Check the communications interface, cables and con-
nections. Make sure the serial interface is set accord-
ing to the manufacturer’s instructions.
• To test an EIA/TIA-232 interface, purchase an EIA/
TIA-232 tester with LED indicators. Attach the tester
between the controller and the computer. When the
computer sends data to the controller, the TX LED on
the tester should blink. When the computer receives
data from the controller, the RX LED should blink.
• You can also connect an oscilloscope to the transmit or
receive line to see whether data is being sent or re-
ceived. If the serial port does not appear to be working,
the software setup may need to be modified or the
hardware may need to be repaired or replaced.
Communications
Most communications problems are due to incorrect wiring
or incorrectly set communications parameters. Therefore,
when there is a problem, check the wiring and communica-
tions settings first. Verify the following:
• Communications Port: Software must be config-
ured to use the communications port to which the con-
troller is connected.
• Software Protocol: The CPC400 supports the Mod-
bus RTU protocol.