One of the guys that used to work here would tell customers who had a troubleshooting question, "Read the book, don't wait for the movie!" (he was kidding, of course)

But, now, you can watch the movie - the troubleshooting movie, that is.

Qualitrol International has launched its Library of PLC Troubleshooting videos.  Topics covered include changing batteries in various GE 90-30, 90-70, and Versamax CPUs; setting up network communications for Allen-Bradley ControlLogix PAC systems; and many others. 

You can check our video collection on our PLC Tech Support Video page.

We have found that these short, concise videos are a great way to demonstrate some basic troubleshooting techniques.  Sometimes it can be difficult to try and explain techincal ideas over the phone - we've all been there.  And with the wealth of knowledge of our PLC engineers, it is a great way for them to show you how to do certain tasks and then make them available for you to use anytime.

We find that many younger maintenance personnel charged with supporting controllers in many factories are not familiar with even the simplest tasks in some older PLC systems.  It's not their fault - it's just that PLCs can last so long and they can stay in production for decades.  It's hard to expect an engineer who has only been out of school 5 years to know how to support a PLC that has been on the market for 20 years!

If you ever have question for our PLC techs, please call or email.  They are available to walk you through any troubleshooting situation.  Heck, they might even make a video about it.

Recently, we had a customer who wanted to upgrade from a GE IC693CPU364 to a GE IC693CPU374 because they believed the CPU374 had more password characters.  Here is our Senior PLC Engineer's answer:

No, it is not true. The maximum length of the password is 6 ASCII characters whether it is an IC693CPU364 or an IC693CPU374. The only length restrictions that I have found is if the user is using Logicmaster 90 or a Hand Held Programmer, both of which limits the length to 4 ASCII characters. I have done some testing and I have found that the password can contain any ASCII character except a space and a tab and it is case sensitive. I believe this will fulfill the complexity requirement for your applications.

As far as the CPU364 is concerned, it would be better if they were replaced by CPU374s because the CPU364 has been discontinued for a few years. The programs in the CPU364 are directly transportable to a CPU374. All that would be needed would be a configuration change in the folder. The primary ‘gotcha’ in converting to CPU374s is that the CPU374 will use up the standard battery after 5-6 weeks of power-down time (versus 6 months for the CPU364). I would recommend that if CPU374s are installed, an auxiliary battery (IC693ACC302) should be installed with each one. This will provide 15 months max. power-down backup capability. An alternative to the CPU374 would be to use the CPU372, which has half the memory capacity at a lower price. However, this would require converting their programming s/w from VersaPro to Proficy Machine Edition (VersaPro does not support the CPU372) and making sure that a high capacity power supply is used with the CPU (Proficy requires that a high-capacity p/s be used with the CPU372 and CPU374).  (To learn how to install an IC693ACC302 for use with an IC693CPU374, go to our video library).

In addition, Qualitrol International will buy any used IC693CPU364 modules that you take out of a system.  Simply call us at 1-800-784-9385 and we will give you all of the details. 

Further documentation on the GE PLC family batteries:

Battery Part Number for VersaMax PLC

Refer to GFK-1503C page 4-11:

The CPU module is shipped with a battery already installed. The battery holder is located in the top side of the CPU module. Before the first use, activate the battery by pulling and removing the insulator tab.

To replace the battery, use a small screwdriver to gently pry open the battery holder.

Replace battery only with one of the following:

GE Fanuc IC200ACC001 --- CPU battery and Holder

Panasonic BR2032

Battery Part Number for VersaMax Micro PLC

Refer to GFK-1645C page 9-23,

For the 23 and 28 point Micro PLCs, a lithium coin cell can be installed in the battery holder and inserted into the front of the Micro PLC behind the removable door. Its purpose is to protect the RAM memory contents of the PLC when the PLC power supply is removed or turned off. It also backs up the CPU’s real-time clock.

Replace the battery assembly with one of the following:

GE Fanuc IC200ACC403

Hitachi-Maxell CR2032WK

Battery Part Number for S9030 PLC

IC693ACC301 --- Battery lit for 9030 CPU and PCM (qty 2)

IC693ACC302 --- External Battery Module

Battery Part Number for S9070 PLC

IC697ACC701 --- Battery lit for 9070 CPU and PCM (qty 2)

Battery Part Number for PACSystem RX7i

IC698ACC701 --- A three-cell lithium battery and spare door

We came across this document today that we thought might be helpful in understanding the capacity of Battery back-up and Capacitor back-up of programs in GE Versamax PLCs,  GE 90-30 PLCs, GE 90-70 PLCs, and PAC systems:

GE PLC Battery and Capacitor capacity

For VersaMax CPUs

Refer to IPI of VersaMax CPU modules:

• Battery backup for program, data, and time of day clock
• Super capacitor provides power to memory for 1 hour
• Over 1 hour, backup battery protects memory contents up to 6 months.
• Backup battery has shelf life of 5 years when not in use.

The part number is IC200ACC001.

For VersaMax Micro 23/28 point PLC

Capacitor backs up RAM and the Time-of-Day clock for at least 30 minutes.

Lithium battery (IC200ACC403, optional battery):

Shelf Life: Up to 5 years typical at 30 °C, Up to 3 years typical at 55 °C

Installed: 4 months battery backup time (powered down) minimum at 55 °C

For VersaMax Micro 14 point PLC and Nano PLC

Capacitor backs up RAM for at least 3 days.

There is no optional battery for 14 point Micro and Nano PLC.

For Series 9030 PLC

Super Capacitor:

The PLC power supply supplies 5 VDC to the memory circuits, including the super capacitor. Therefore, when PLC power is turned off, the super capacitor has an initial 5 VDC charge. If the battery is also disconnected shortly after PLC power is turned off, the super capacitor will begin discharging from the 5 VDC level until its charge reaches 2 VDC, at which time memory contents will be lost. When used this way, the super capacitor can maintain memory contents for a minimum of 1 hour.

The memory backup battery supplies 3 VDC to the memory circuits, including the super capacitor. Therefore, if PLC power has been turned off for an hour or more and only the battery is powering the memory circuits, the super capacitor has a 3 VDC charge. Then, if the battery is disconnected, the super capacitor will begin discharging from the 3VDC level until its charge reaches 2 VDC, at which time memory contents will be lost. When used this way, the super capacitor can maintain memory contents for a minimum of 20 minutes.

Battery: IC693ACC301 battery lit for 9030 CPU and PCM (qty 2)

A battery that is used continuously (supplying current to memory circuits with PLC power off), if used at room temperature, has an estimated average life as follows:

The voltage threshold for the BATT LED to come on in a 90-30 powers supply is 2.5V DC +/- 5%

External Battery Module (IC693ACC302)

This module provides long-term battery backup for all modular Series 90-30 CPUs. Its two-foot cable plugs into the power supply battery connector. The External Battery Module maintains RAM contents on a CPU374 and NIU004 for 15 months. CPU models 331—364 maintain RAM contents for approximately 75 months.

For Series 9070 PLC

IC697ACC701 battery lit for 9070 CPU and PCM (qty 2)

A battery that is used continuously (supplying current to memory circuits with PLC power off) has an average estimated life of 6 months, if used at room temerature.

The voltage threshold for the BATT LED to come on in a 90-30 powers supply is 2.5V DC +/- 5%

For PACSystem RX7i PLC

IC698ACC701 --- A battery that is used continuously (supplying current to memory circuits/calendar with system power off) has a minimum estimated life of 40 days.

If want to keep program forever, write HWC and Logic into Flash memory.

Here is a troubleshooting question from one of our GE Fanuc 90-30 PLC customers and the response from our GE PLC Engineer:

Question:  We have GE Fanuc PLC Series 90-30 in our imported Textile machine. PWR and OK LEDS are green but RUN LED is not glowing on IC693PWR321 module of PLC. Also Communication error is displayed on Operating station. Is program of PLC corrupted or lost ? or any other problem ? Please give us your suggestion to solve the problem

Answer:  The Power LED indicates that the power supply has powered up OK and that its outputs are within tolerance. The OK LED indicates that the CPU has powered up and has passed its power-on self test. The RUN LED indicates that the CPU is in either Stop or Stop/Faulted mode. Is the Battery LED on? If so, the battery’s output is too low and it is very possible that the program and the configuration are lost.

In order to determine what stopped your CPU, you need to connect to the PLC with the appropriate programming software (Logicmaster 90-30, VersaPro Standard or Proficy Machine Edition Logic Developer PLC Standard) and examine the Controller and I/O fault tables. If you do not have one of the programming software packages, you will need to obtain one of them along with a programming cable in order to examine the fault tables and reload the program and configuration if necessary.

If your Operator Station is not communicating with the PLC, this could be due a defective communication cable, PLC port or Operator Station port. It could also be due to improper communication settings in the PLC or the Operator Station. Improper settings in the PLC could be due to a corrupt program or configuration in the PLC but I cannot tell you for certain until you examine the PLC’s fault tables and memory with the programming software.