PLCIO is The Tool You Need for Simplifying PLC Library Communications
Written especially for enterprise and industrial users who need PLC communications for Linux/UNIX platform computers, PLCIO simplifies library communications.

PLCIO 4.5.2
Released November 14, 2017

PLCIO 4.6.0
Coming August 2024

PLCIO Currently Supports PLC Models from the Following

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PLCIO is written especially for enterprise and industrial users who need PLC communications for Linux/UNIX platform computers.

Celebrating 30 years of PLCIO- PLCIO was born from the need to provide a simple, but effective communications interface to talk to I/O devices. Our primary objective was to abstract the application and communications layers so that someone programming the business and database logic would not have to worry about the communication details.

Very light-weight – does not require any custom hardware or specialized drivers. Ethernet and serial protocols supported.

Easy learning curve - PLC communications protocol experience is not required.

Source code distribution is setup for maximum flexibility, maintainability and integration, now and in the future.

Enterprise Applications for PLCIO:
  • Warehouse management
  • ASRS (automated storage and retrieval systems)
  • Tracking/barcode
  • Embedded control systems
  • Or whenever sophisticated data systems need access to PLC automation technology

PLCIO version 4.5 includes support for the following PLC types:

  • AEG Modicon Quantum PLC via Ethernet
  • Allen-Bradley Logix 5000 family (ControlLogix, CompactLogix, FlexLogix, SoftLogix) via EtherNet/IP
  • Allen-Bradley MicroLogix via EtherNet/IP
  • Allen-Bradley PLC-5 via DF1 serial, Ethernet, or EtherNet/IP
  • Allen-Bradley SLC 500 series via DF1 serial, Ethernet, or EtherNet/IP
  • Modbus RTU modules over serial
  • Modbus TCP/UDP modules over Ethernet
  • Omron C/CS/CJ-series CPUs via Host Link over serial
  • Omron CS/CJ-series CPUs via FINS over TCP, UDP, EtherNet/IP, or serial
  • Siemens Step5 via AS511 serial protocol
  • Siemens Step5 via INAT Echolink over Ethernet
  • Siemens S7-200/300/400/1200/1500-series CPUs via Ethernet
  • Wago 750-842 PLC via Ethernet with optional unsolicited UDP support

PLCIO communicates to EtherNet/IP Bus Terminals. These terminals have been tested specifically:

  • Beckhoff BK9105 over EtherNet/IP
  • Phoenix Contact FL IL 24 BK ETH/IP-PAC over EtherNet/IP

Supported Operating Systems:

  • GNU/Linux -- GLIBC 2.0 or later, Linux kernel 2.2 or later
  • HP-UX 11 -- HP aCC (cc) or gcc build environment
  • AIX 7 -- IBM XL C (xlc) or gcc build environment
  • Windows XP and later -- MSYS/MinGW build environment
  • FreeBSD 10 -- clang or gcc build environment
  • Other UNIX systems on request

Frequently Asked Questions

Q. The runtime for PLCIO is sold by CPU license. What is a CPU?
A. For PLCIO, we define a CPU as an active production computer running PLCIO. If this computer is one small Pentium 3 or a huge four CPU Quad Core Xeon processor box, both are defined as One CPU. If there are two computers are running as a cluster, one CPU license is needed for a failover cluster; two (or more) are needed as a “load balanced” cluster. The spirit of our CPU license is “active production” computers.

Q. Regarding the "virtual" module, there are only two tags: RAW1 and RAW2. What if I need more addresses to store data?
A. You can use the "tagname(offset)" syntax with these tags. As shipped, RAW1 is 200 bytes in size and RAW2 is 2000 bytes in size. Therefore if you were working with 16-bit integers, you can store 100 integers in RAW1 and reference them as RAW1(0), RAW1(2), RAW1(4), and so on. If you need to increase the size of the tags, you can edit the VIRT_RAW1_SIZE and VIRT_RAW2_SIZE #defines in so/virtual.c and recompile the library.

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