CHAPTER 4: MAINTENANCE AND TROUBLESHOOTING
SNAP PAC R-Series Controller User’s Guide
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make sure it is still good, and closes it if it is not. The default is 240,000 milliseconds, or
four minutes.
5.
Click the Apply button to write your changes to the controller.
6.
In the Operation Commands list, highlight Store configuration to flash. Click Send
Command.
7.
In the Operation Commands list, highlight Restart brain from powerup. Click Send
Command.
The new TCP parameters are set.
Troubleshooting I/O Modules: Frequently Asked Questions
SNAP Digital Troubleshooting
Q: I have a SNAP digital module that has ceased to function. What may have caused
this?
A: Loss of function in a SNAP digital module is normally caused by misapplication. As with
Opto 22’s other digital I/O module families, there is no one way in which SNAP I/O modules
fail. Output modules normally fail in a different way than inputs.
Output modules usually fail open, or half-wave for AC, and the failure is normally caused by
the application of too much current or by degradation of the semiconductor switch by
overvoltage.
Because the module is separated into two parts by the optical isolator, it is possible to have
an output module that behaves properly on the logic side but is broken on the field side.
The LED will in most cases continue to turn on and off as commanded by the driving logic
device, even though the module has failed.
The first step to troubleshooting a failed module is to check the fuse. If it is blown, simply
replacing it should get the module working again. If the module continues to blow fuses,
analyze the load to see if the module is really suitable to the application.
When input modules fail, they usually do so on the field side, typically from overvoltage or
overcurrent resulting from overvoltage. Opto 22’s SNAP AC and DC input modules contain a
full-wave rectifier (as opposed to the G1 and G4 modules, which contain a bridge rectifier),
allowing hookup without regard to polarity. Unlike output modules, an input module’s LED
normally will not function as expected when the module has failed.
Failures on the field side of all types of Opto 22 digital I/O modules occur extremely rarely
and are typically the result of misapplication. The logic-side failures of Opto 22’s I/O
modules are also extremely rare. Usually, a failure of the logic side is attributable to using
the module at the wrong logic voltage or to miswiring.
