The information on this web page is either Lynn's opinion or something Lynn agrees with. He has complete control over its contents. Nothing contained within this pages is approved by or represents the opinion of Digi International, The Modbus Organization, the Modbus-IDA Group, ODVA, or any other organization Lynn is associated with.

Protocol Overview

My plan is to create simple overview of the more common serial protocols one encounters in the IA world. However, I'll never be as complete as Rob's Fieldbus Pages. So check there for protocol questions NOT answered here.

Omron

• Omron PLC site - as-of April-2004
• Q: What is Omron HostLink?
• Q: What is Omron FINS or FINS/UDP?
• Q: Can DigiOneIAP be used with an Omron PLC?

Omron has a fairly good collection of manuals on-line. As of April-2004 you can find the index for manuals here Omron Document Library. Then click the"Programmable Logic Controllers (PLCs)" and then the arrow by the "Manual" to see many pages of Manuals.

Question? What is Omron HostLink?

Answer: An ASCII-based RS-232 protocol that can be used for most Omron PLC.

The good of HostLink: seems pretty universal. The bad: is slow (ie: a 16-bit value ends up as 4 bytes of ASCII) and can only move about 30 words per message. Larger messages are moved by a 'fragmentation' process, where the same slave returns a series of messages to build up the entire response. It is also limited to 32 nodes per multi-drop.

A basic HostLink manual is titled "SYSMAC: C-series Rack PCs: SYSMAC WAY: hostLink Units" and can be found by searching for 'W143-E1-6' or 'M11W143E161100.pdf' in the document library. This manual describes all the HostLink commands, plus shows any limitations in support based on PLC model.

Another one is 'W205-E1-3A' - not sure it is any better or worse.

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Question? What is Omron FINS?

Answer: Omron's newer, network based protocol - usually via UDP/IP port 9600.

Since most newer PLC can also encapsulate FINS commands via HostLink some people may mistakenly think they are the same or one is a subset of the other. But FINS is a 'new' set of commands and a fairly large header to support inter-network 'routing'. FINS is moved within HostLink by a new command that says "this is encapsulated FINS". But given the ASCII nature and 30+word limitation of HostLink it becomes very slow to move true FINS commands by HostLink. Fragmentation will be great.

There are a couple of good manuals online for FINS.

The first is titled "FINS Commands: reference Manual" and can be found by searching for 'W227-E1-1' or 'M11W227E11299.pdf' in the document library. This manual describes all the FINS commands, plus shows any limitations in support based on PLC model.

The second is titled "SYSMAC CS and CJ Series ... Ethernet Units: Construction of Applications" and can be found by searching for 'W421-E1-01' or 'M11W421E1011003.pdf' in the document library. This manual describes how the FINS commands are placed into UDP/IP or TCP/IP. It also nicely includes UNIX application examples in "C" to poll a FINS PLC.

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Question? Can DigiOneIAP be used with an Omron PLC?

Answer: Yes, but Omron has a specially packaged OEM version.

Part Number is CPM2-ET1-L1. I encourage you to buy them through Omron. Lets face it - there are a lot of Omron PLC models out there and Digi Support won't know the difference between a CH200, CS1 or CJ1M. The current firmware understands HostLink message fragmentation and routing on the slave address. It supports the following applications:

• HostLink serial from Host applications to 'virtual comm' ports (ie: Digi RealPort)
• HostLink serial encapsulated into TCP or UDP - for example from an OPC server such as Kepware.
• HostLink serial tunnelled between 2 or more DigiOneIAP units

Omron has 2 'quick-start' guides on-line:

The first is for a serial tunnel, meaning an existing HostLink serial Master connects to one DigiOneIAP, and this links by Ethernet to one or more remote DigiOneIAP. The DigiOneIAP by the HostLink master will use the node address to select one of up to 12 remote IP to connect to and will be sending HostLink encapsulated in TCP. It can be found by searching for 'PDG1FAZ1' or 'M11PDG1FAZ10303.pdf' in the document library.

The second is for using Digi RealPort to allow host computers to directly use serial HostLink via Ethernet without the local unit being required. It can be found by searching for 'PDG2FAZ1' or 'M11PDG2FAZ10303.pdf' in the document library.

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