POINT I/O 1734 Selection Guide
In industrial process controls, certain applications benefit from having field devices such as sensors and pushbuttons wired short distances to local I/O nodes, instead of wiring long distances back to a central PLC. These distributed I/O nodes serve as the interface between individual field devices and the separate control network (usually running Ethernet/IP or ControlNet protocols) and provide the benefits of reduced installation cost, fewer full PLC racks, and improved diagnostic features positioned near the field devices. Several automation manufacturers offer these types of distributed I/O products, though Rockwell Automation’s POINT I/O family stands out from the crowd as a premier solution for both small and large applications. Read on for an in-depth look at the POINT I/O modular wiring hardware family, its features, and its role within Rockwell’s Integrated Architecture ecosystem.
POINT I/O Family Overview
The complexities of modern process control can seem to extend in every direction - not just in terms of the processes being controlled, but in the constantly evolving technologies that provide this control, to begin with. Rockwell Automation’s approach to simplifying control solutions is their Integrated Architecture methodology, which they describe as a ‘production control and information system allowed by fully-integrated control, network, visualization, and information technologies’. The best way that we can plainly translate this description is to say that Rockwell’s Integrated Architecture is the umbrella of controllers, operator interfaces, industrial computers, network media, motor & motion control devices, I/O devices, safety devices, visualization tools, and distributed control systems that all share a programming environment. This entire ecosystem is completely cross-compatible, based on a common network technology across all hardware, applications, and process operations, plant-wide.
As a member of the Integrated Architecture portfolio, Rockwell Automation / Allen-Bradley’s Bulletin ##1734 POINT I/O is a family of modular I/O connectivity hardware that serves the purpose of wiring in field devices to an Integrated Architecture system. This might be a single machine with a PLC and POINT I/O rack in the same cabinet, or all the way up to multiple PLCs and multiple POINT I/O racks spread across a large plant with interconnecting Ethernet/IP communication.
Beyond simply offering a distributed wiring solution for field devices, POINT I/O has a variety of additional features intended to standardize and speed up deployment, reduce engineering costs, and improve system reliability. We’ll dive into these benefits in the next section.
POINT I/O System Features
Rockwell Automation’s POINT I/O family is marketed under the following key benefits:
- Flexibility
- Connectivity to ControlNet, DeviceNet, Ethernet/IP, and other open networks
- Linear, star, and ring Ethernet/IP network topology
- Supports IO-Link Technology
- Individual, rack, and assembly-level connections
- Horizontal or vertical mounting without derating
- Safe and Standard I/O in the same chassis
- Cost savings
- Modular design requires less enclosure space
- Up to 504 channels on a single network interface
- Removable terminations accelerate commissioning
- Remove and Insert Under Power (RIUP) reduces maintenance time
- Local autonomous control
- Ease of use
- Fast, simple configuration and integration
- Channel-level diagnostics
- Faster performance
- Multiple connection types
- Sense-to-actuate time of less than 2 milliseconds
The above benefits are certainly impressive for I/O connectivity hardware, but does the family offer enough I/O choices to make an investment in POINT I/O worthwhile? We argue, yes - POINT I/O modules span practically all I/O types needed on a process control project, including:
- Bulletin ##1734 digital I/O modules
- Bulletin ##1734 analog I/O modules
- Bulletin ##1734 specialty I/O modules
- Bulletin ##1734 wiring systems
- Bulletin ##1734 network communication adapters
- Bulletin ##1734 POINT Guard I/O Safety modules
Pulling additional features from the wider Integrated Architecture ecosystem, POINT I/O also provides comprehensive channel-level diagnostics such as wire-off and short circuit detection, as well as configurable features such as user-settable filters and alarms.
Point I/O is the only IP20-rated modular I/O solution complaint with ODVA requirements for linear, star, and ring Ethernet/IP architectures, providing greater system reliability and availability. (See below for more on ring network options).
Lastly, POINT I/O offers an IO-Link Master module, allowing up to (4) IO-Link devices to be connected to each POINT I/O rack. IO-Link is the first technology used for direct connection to sensors and actuators to be adopted as an IEC 61131-9 standard.
Key POINT I/O Selection Details
The POINT I/O system has four major components, as described in Rockwell’s POINT I/O Module Selection Guide, document number 1734-SG001G-EN-P, dated September 2019:
- I/O modules provide the field interface and system-interface circuitry
- Communication interface modules provide the network-interface circuitry
- Terminal base units provide the wiring and signal termination for field-side connections and system power for the backplane
- Power distribution modules provide the expandability of the POINT I/O system and the flexibility to mix a variety of signal types
Looking further, POINT I/O modules offer between 1 and 8 points each, of which we can have between 13 to 17 I/O modules per communication interface (network adaptor). Modules pull power from the communication interface via the backplane, for a max of 10A field power draw per rack. Alternatively, using an optional external power supply, these counts can be expanded to a maximum of 63 I/O modules or 504 channels. Modules are available as either Removable Terminal Designs or one-piece Terminal Bases / Spring Clamp designs.
Network adaptors are available in multiple Open Network Architecture protocols, including ControlNet, DeviceNet, Ethernet/IP, and Profibus. Each of these protocols uses the Common Industrial Protocol (CIP), sharing a common language and universal set of communication services – a namesake feature of Rockwell’s Integrated Architecture approach. A unique feature of POINT I/O is its ability to mix Standard and Safety-Rated I/O types in the same rack, each with its respective configuration, monitoring, and diagnostic services fully available.
- The Ethernet/IP network is an open industrial-networking standard that supports implicit and explicit messaging and uses commercial, off-the-shelf Ethernet equipment, and physical media.
- The ControlNet network allows intelligent, high-speed control devices to share the information required for supervisory control, work-cell coordination, operator interface, remote device configuration, programming, and troubleshooting.
- The DeviceNet network offers low-cost, high-speed access to plant-floor data from a broad range of plant-floor devices and a significant reduction in wiring.
To help envision how POINT I/O is installed in a network, we can see in the below graphic that a POINT I/O rack is connected via Ethernet/IP (or any of the other protocols) away from our PLC/PAC racks. POINT I/O must always be installed in a cabinet, but it is equally useful to install POINT I/O in the PLC cabinet for centralized wiring as it is to install in a remote cabinet for wiring close to field devices.
To speak a little further about the available ring network topology, POINT I/O fully supports Device Level Ring (DLR) configuration. DLR is an Ethernet/IP protocol that is defined by the Open DeviceNet Vendors Association (ODVA), which provides a means to detect, manage, and recover from single faults in ring-based networks. Ring networks are advanced configurations that land two Ethernet cables on a given control device, creating two paths for data transfer that help insulate against the failure of a single node in the network (which is an inherent risk in single-branch network topologies commonly selected due to lower costs).
Complete Selection
Sometimes, seeing the complete breadth of options in a hardware family is the only way to absorb the true capabilities and benefits available with that technology. We’ll close out our article by posting the full list of POINT I/O modules and accessories below. Note a few available options that might surprise you in an I/O rack-only platform, including:
- Under Specialty Products, the ‘VHSC’ modules are ‘Very High-Speed Counters’, rated up to 500kHz
- 220VAC rated relay inputs and outputs
- Self-Configuring Discrete I/O
- Cold-Junction Compensation modules for use with thermocouples
- Address Reserve Modules (1734-ARM) for reserving addresses and slot numbers, maintaining numbering schemes when replacing or spacing out signal modules
The full list of POINT I/O modules and accessories may be seen below.
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Adapter Products
- 1734-AENT, 1734-AENTR, 1734-ACNR, 1734-ADN, 1734-ADNX, 1734-APB
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Digital Output Products
- 1734-OB8, 1734-OB8E, 1734-OB4, 1734-OB4E, 1734-OB2, 1734-OB2E, 1734-OB2EP, 1734-OV8E, 1734-OV4E, 1734-OV2E
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Self-Configuring I/O Products
- 1734-8CFG, 1734-8CFGDLX
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Digital Input Products
- 1734-IB8, 1734-IB4, 1734-IB4D, 1734-IB2, 1734-IV8, 1734-IV4, 1734-IV2
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Analog Products
- 1734-IE2C, 1734-IE4C, 1734-IE8C, 1734-IE2V, 1734-OE2C, 1734-OE2V, 1734-OE4C, 1734-IR2, 1734-IR2E, 1734-IT2I
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AC and Relay Products
- 1734-OW2, 1734-OW4, 1734-OX2, 1734-IA2, 1734-IA4, 1734-IM2, 1734-IM4, 1734-OA2, 1734-OA4
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Specialty Products
- 1734-4IOL, 1734-232ASC, 1734-485ASC, 1734-VHSC24, 1734-VHSC5, 1734-IK, 1734-IJ, 1734-SSI, 1734-ARM, 1734-CTM, 1734-VTM
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Power Supply Products
- 1734-EP24DC, 1734-EPAC, 1734-FPD, 1734-PDN
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Terminal Bases and Accessories
- 1734-TB, 1734-TBS, 1734-TB3, 1734-TB3S, 1734-TBCJC, 1734-TOP, 1734-TOPS, 1734-TOP3, 1734-TOP3S, 1734-EXT1, 1734-EXT3
