Understanding the 17xx | Your Rockwell/Allen-Bradley Hardware Encyclopedia
Rockwell Automation’s Allen-Bradley control hardware catalog has long included many series that start with 17xx, but what are these lineups, and what function do they serve?
For many generations, engineers that use Allen-Bradley hardware products (now owned by Rockwell Automation) have faced numerous series of part numbers that maintain compatibility within each series, but sometimes have difficulty working with new, or legacy systems, depending on the series. This can complicate designs, forcing engineers to dig through spec sheets to learn what I/O modules might work with which PLC processors.
To address this confusion, I have compiled a list of all the 17xx product series from Allen-Bradley, along with brief descriptions and current product lifecycles.
Buckle up and enjoy the ride through this rather lengthy catalog of PLC components.
Hint: to quickly find one product, press ctrl/cmd-f and type the part number or name you wish to find.
1715 Redundant I/O System
Active Product
These chassis-based digital and analog I/O modules provide fault tolerance. When working as Ethernet remote I/O units with a ControlLogix PLC, any fault in a module will cause the PLC to immediately switch over to monitoring an alternative identical set of I/O modules.
1718 Intrinsically Safe I/O Zone 1
Active Product
This series of I/O modules is for Ethernet/IP distribution in hazardous areas. Integrates with Studio 5000 Logix Designer controllers. It includes digital, HART, and temperature inputs, and digital output modules.
1719 Intrinsically Safe I/O Zone 2
Active Product
This distributed I/O series is similar in features to the 1718 series, but with enhanced conformity to intrinsically safe guidelines for installation in Zone 2 hazardous environments.
1720 Cardlock State Logic Controller
Retired Product
One of the earlier (1970s) commercial PLC systems consisted of a chassis, power supply, and logic gates integrated right into the modules. Rather than being strictly ‘programmable,’ this system was instead a configurable, dedicated set of individual logic gates, timers, and counters that has since been replaced with more user-friendly, efficient PLCs.
1722 Modular PLC
Retired Product
This chassis-based PLC is also one of the oldest series of PLCs using cards installed into slots on a chassis. Not much information is readily available about this system, so if you have further info, please contact [email protected], as we would love to learn more.
1732 ArmorBlock I/O
End-of-Life Announced for Some Products (late 2023)
This I/O hub is designed for installation directly on a machine with sealed Ethernet/DeviceNet communication and I/O connection ports.
1734 POINT I/O System
Active Product
This product line is quite familiar to many engineers. While it does not contain control logic, it provides connections for remote digital and analog inputs and outputs, as well as various communication protocol support. The modules are also used to expand ConpactLogix PLCs with embedded I/O points.
1738 ArmorPoint I/O
Active Mature Product
Tough, durable distributed I/O and communication modules for direct installation on a machine. This series includes digital and analog I/O with a few specialty modules and ControlNet/DeviceNet communication adapters.
1742 Modular Automation Controller (MAC)
Retired Product
This was one of the first modular styles of controllers, developed in the early 1980s (bonus: the MAC self-team manual here, this is really cool stuff). This system contained a central ‘rack’ with removable AC and DC I/O, along with a processor and memory modules. Programming was accomplished with an external operator terminal.
1745 SLC 100/130/150 PLCs
Retired Product
Although expandable, this SLC series is the embedded I/O version of the SLC 500 PLC series, a familiar site for engineers with a few years of experience in the field. This PLC was also programmable via a PC with an RS-232 cable. (Bones, check out the docs and self-teach manual here)
1746 SLC 500 I/O Modules
Retired Product
Ah, who doesn’t know and love the “Slick 500” PLC? The 1746 series includes the chassis and the digital, analog, and specialty I/O modules compatible with the CPUs, which are part of the following 1747 series.
1747 SLC 500 CPU and Communication Modules
Retired Product
The 1747 series of components features the CLS 5/01 through 5/05 CPU models, along with many of the more modern communication adapters (Ethernet, DH-485, etc.)
1752 SmartGuard Safety Controller
Discontinued at End of 2023
The safety controller is a middle ground and first line of defense for safety field devices. Optional DevieNet and Ethernet communications can interface with PLCs for system performance, but the safety controller directly works with safe I/O field devices for instant response.
1753 GuardPLC 1200 Safety PLC
Retired Product
This device is a dedicated safety PLC, replaced now by more flexible modular CPUs and I/O combinations alongside a typical PLC chassis. This GuardPLC series contains not only the CPU (controller) but also distributed I/O blocks.
To save time, we’ll also note that the GuardPLC series also includes the following:
1754 GuardPLC 1600/1800 Safety PLC
1755 GuardPLC 2000 Safety PLC
1756 ControlLogix PLC
Active Product
Here we arrive at one of the two top choices for med/large industrial application solutions from Rockwell! The ControlLogix PLC family includes chassis, CPUs, communication adapters, and I/O modules for an endless variety of local and distributed solutions. If you haven’t learned this PLC system (hardware and programming), I recommend you contact your nearest technical college or training company and get some hands-on experience. It will pay great dividends in all your future control system work.
1760 Pico Controller Micro PLC
Retired Product
This tiny PLC contains only a few digital inputs and relay outputs, but it can be programmed right on the included HMI. It’s quite basic, but effective for very small machines with limited functionality and I/O requirements. It has been replaced by the more modern Micro800 PLC system.
1761 MicroLogix 1000 PLC
Retired Product
I love this PLC because it was one of the first PLCs that I actually owned and could program at home. I still have four of these little guys. Built with embedded I/O points and limited communication capabilities, they have also been replaced by the updated Micro800 series. The free programming software (RSLogix Micro Starter Lite) is becoming more difficult to locate.
1762 MicroLogix Expansion I/O
Active Mature Product
These expansion I/O modules, including digital and analog inputs and outputs, are designed for the MicroLogix 1100, 1200, and 1400 series, but not the 1761 MicroLogix 1000.
1763 MicroLogix 1100 PLC
Retired Product
These small PLCs also include embedded I/O, much like the MicroLogix 1000 series, but allow expansion by use of the 1762 series of I/O modules.
1764 MicroLogix 1500 PLC
Retired Product
This small PLC allowed manual expansion of program memory and accepted I/O modules from the CompactLogix series. The series also included plug-in base units that provided I/O points much like the form factor of PLCs with embedded I/O along the top and bottom that we see today. This PLC could only be programmed with a licensed ‘lite’ version of RSLogix 500.
1766 MicroLogix 1400 PLC
Retired Product
This final PLC in the discontinued MicroLogix family also includes embedded I/O and the ability to add on more modules from the 1762 series, making it quite similar to the MicroLogix 1100 series. The entire catalog of MicroLogix PLCs has been replaced by the more modern Mirco800 series.
1768 CompactLogix CPU
Retired Product
Although CompactLogix PLCs are alive and well, the L43 and L45 CPU modules have been discontinued. This modular PLC differs from the ControlLogix (1756) in that it doesn’t require a base chassis (backplane). The modules and power supplies are attached together right onto the DIN rail mounting.
1769 CompactLogix PLC System
Mostly Active
This product series includes a wide variety of power supplies, CPUs, communication adapters, and I/O modules. One convenient form factor in the L1x and L2x processor lines (such as the 1769-L16ER, one of the first PLCs I purchased and learned modern tag-based programming) includes embedded I/O, with digital and analog options. The remainder of the processors use the expansion I/O modules for a flexible setup.
1771 PLC-5 Chassis, Power Supply, and I/O Modules
Retired Product
One of the classic PLCs that is still found running in occasional installations, the PLC-5, has a product line that covers the hardware aside from the CPU. Multi-slot chassis, various power supplies, and I/O modules have been discontinued and are usually replaced by CompactLogix or ControlLogix hardware configuration.
1772 PLC-2 System
Retired Product
The 1772 products are the CPUs (controllers) that work with the 1771 series of racks and modules in the PLC-2 system, pre-dating the PLC-5 controllers.
1773 Microtrol PLC-4 System
Retired Product
This small PLC, also long since retired in favor of the more modern CompactLogix, contained embedded I/O points but also allowed expansion with basic I/O modules. It was programmed using a handheld input terminal.
1774 First “PLC”
Retired Product
According to online sources, this is the first controller to adopt the name of “programmable logic controller,” using a hand-held programmer, and, of course, quite basic compared to the PLC systems we employ in facilities today.
1775 CPUs for the PLC-3 System
Retired Product
This family of early PLC products includes CPUs, I/O scanners, and communication modules.
1778 Remote I/O System
Retired Product
This expansion I/O series includes power supplies, I/O modules, and communication for early distributed I/O applications. Not much information is readily available about this system, so if you have further info, please contact [email protected], as we would love to learn more.
1783 Stratix Network Devices
Active Mature
The Stratix managed network switches are not controllers, but they do allow for expansion of a networked system with many configuration options.
1785 PLC-5 CPU Modules
Retired Product
This product series includes the well-know (but not found often anymore) PLC-5 series. The 1775 series includes CPUs, memory modules, and some communication interfaces and is designed to work with the 1771 series of I/O modules.
1789 SoftLogix PLC
Retired Product
A software-defined PLC acts exactly like a real hardware PLC, but is instead a digital recreation used for simulation and replication of a real product. The products are PC interface cards and software, but they connect to real-world distributed I/O to virtualize the PLC experience.
1790 CompactBlock I/O
End-of-Life
These small blocks include an embedded DeviceNet adapter to provide expansion digital, analog, and temperature I/O into an existing PLC system.
1791 Block I/O
Retired Product
This series contains a number of AC and DC discrete I/O modules that interact directly with older PLC without requiring a bus adapter. They are compatible with PLC-2, PLC-3, PLC-5, and some SLC 500 processors.
1792 ArmorBlock Machine I/O
Retired Product
This I/O block is meant to be installed directly on the machine, with ruggedized connections and casing to provide superior protection. This product line has been replaced by the 1732 series of devices.
1793 FLEX Integra Analog Modules
Retired Product
This set of analog I/O modules is part of the FLEX I/O family, but employs a ‘block’ communication method primarily used with the PLC-5 and SLC 500 systems. It can be installed along with standard FLEX I/O, but is not typically used in newer installations.
1794 FLEX I/O System
Active Mature
The FLEX I/O family is a very popular modern choice for distributed I/O, allowing a central CPY to control a system with power, communication, and field I/O connected to various machines.
1797 FLEX Ex I/O
Retired Product
This I/O system was designed for intrinsically safe (explosion-proof) situations, and has been replaced by the 1718 and 1719 intrinsically safe I/O product family.
1798 FlexArmor Machine I/O
Retired Product
Field (or distributed) I/O can be in a cabinet or on a machine. If installed on the machine, it must be robust with IP-rated connections. This I/O system, complete with a backplane, creates the modular system to work with FLEX I/O for a comprehensive distributed system. This has been largely replaced by the 1732 I/O system.
That’s pretty much a wrap on Rockwell’s 17xx series lineup, but it’s a long list.
If you’ve used some of these systems (especially the older ones), drop us a note or a comment below and share your experience with us and with future engineers!
