Case Studies

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Improved shipping accuracy boosts bottom-line profits for leading snack food manufacturer. (200K PDF)

House Plant Automation
Ethernet-driven automated watering system is in full-bloom at an 80-acre greenhouse. (196K PDF)

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Tech Support

GE Fanuc PLC Tech Support – FAQs – Series One

Please click below to find the answers to our most Frequently Asked Questions (FAQ):

My Series One PLC quit working; how do I troubleshoot the problem myself?

We offer copies of the manufacturer’s troubleshooting guides for both Series One and Series One Junior PLCs available in the in the Series One Documentation section. If you need additional help, our technical support staff is ready to assist you by phone at 1-866-599-6507 or through email to

How can I view, print, or change the ladder-logic program in my Series One PLC?

There are a variety of methods for communicating with the Series One PLC and the best option will vary depending on what you need to accomplish. Please visit our Series One Programming Tools section

How can I create a backup copy of the program in my Series One PLC?

The Series One and Series One Junior PLCs were designed to allow permanent program backups to be stored on consumer-grade audio cassette tapes. The backup is created by using a Hand-held Programmer unit to transfer data through an audio cable to a cassette recorder. Two versions of the Hand-held programmer were produced: IC610PRG100 and IC610PRG105. We recommend the IC610PRG105 in most cases since this unit supports the advanced functionality of the Series One Plus CPU while still maintaining compatibility with older models.

Almost any cassette recorder with a tone control and an external microphone input can be used, but we have put together a kit consisting of a compatible cassette recorder, batteries, and two cassette tapes. More information on the recorder available by calling our sales representatives at 1-866-599-6507.

What does the “Battery” light on a Series One PLC indicate?

For Series One and Series One Junior PLCs, the battery light on the CPU is turned off during normal operation. If this light is illuminated, the CPU battery should be replaced as soon as possible to ensure that the ladder-logic program contained in the unit’s RAM will not be lost in the event of a power outage. The replacement part number is IC610ACC150.

What does error code E21 on a Series One PLC mean?

Error code E21 signifies a memory parity failure and is one of more frequently seen error codes on Series One and Series One Junior PLCs. This error is displayed when the program data stored in RAM has become corrupt and is no longer valid. It is common for this condition to occur following a temporary power outage in cases where the battery is too weak to retain the program stored in memory. The only way to resolve an E21 error is to reload or reenter the program. In rare circumstances, E21 can also indicate a hardware fault within the CPU itself. Our technical support staff can help you determine whether or not hardware replacement is warranted. We can be reached by phone at 1-866-599-6507 or through email to For information on other error codes, please refer to “Series One Error Code Definitions,” available for download on our Series One Documentation section.

How do I know what a particular Series One PLC error code means?

A table containing descriptions of all possible errors and the actions necessary to correct them, entitled “Series One Error Code Definitions,” is available for download on our Series One Documentation section.

How can I tell if the power supply in my Series One PLC rack is working properly?

One of the most common components to fail in any PLC system is the power supply. The internal components used in all power supplies tend to degrade with use and this normal component aging is accelerated by extreme temperatures and harsh environments. We have prepared a guide, entitled “How to Check Series One Backplane Voltages” on our Series One Documentation section, that describes how to check the backplane voltages on most Series One PLC racks to determine if the power supply is operating within the manufacturer’s original specifications.

Should I upgrade my Series One PLC system to a newer product?

By the late 1980s, the Series One was the top selling small-form-factor PLC in the world. Its exceptional reliability and performance made it ideal for a myriad of applications, and, because of its versatility and robust design, there typically has not been any reason to replace it. In today’s manufacturing world, however, where Ethernet communications, high-speed processors, and Windows-based programming software are all commonplace, the Series One just seems out of place.

While your maintenance team might say "if it isn’t broken, don’t fix it," management is concerned about downtime should the Series One finally expire, and you do not have the time to engineer a seamless conversion that minimizes lost production time. If this sounds familiar, then you are the customer we had in mind when we developed our Series One conversion process. CIMTEC offers a conversion program to replace your Series One PLC system that is fast, cost-effective and let’s you take advantage of modern GE Fanuc PLC technology, specifically the 90-30 PLC system. Click here to learn more about the benefits of upgrading your Series One PLC.