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.

Lynn's White Papers

Protocol Irrelevance (PDF - 59K)

ABSTRACT: One of the true opportunities of Ethernet is its ability to support a large number of protocols at the same time without hardware change. While industrial philosophers bemoan the decades old crusade of "Why can't we all just implement the SAME single protocol ... vendors (especially smaller ones) have no financial choice but to offer the many Ethernet protocols end users request.

Even today Ethernet I/O products exist which offer concurrent support for Modbus/TCP, Ethernet/IP, and several other protocols. Giving the falling cost of flash memory, it's conceivable that within the year Ethernet I/O products will support up to a dozen Ethernet-carried protocols concurrently.

So even without a single, industry-wide protocol, this enables the marketing and application of one-model-fits-all type products. This paper outlines some of the TCP/IP issues that enable this organized chaos, some of the data modeling issues required for concurrent support for multiple protocols, and some product design examples that successfully leverage multiple protocols to produce a whole product that is "greater than the sum of its parts".

Implementing Modbus/TCP; Avoiding Multi-Vendor Pitfalls (PDF - 991K)

ABSTRACT: Today, Modbus/TCP is the richest option for Ethernet users desiring the widest supply of equipment from the most vendors. Even if Modbus is not your native device protocol, you can likely add a simple Modbus/TCP server (ie: answer remote queries) with only a few hundred lines of code. This paper covers the basic implementation issues of adding Modbus/TCP to your Ethernet product, including a range of lessons learned from the field. With over 7 years of multi-vendor Modbus/TCP experience, the writer is well qualified to point out pitfalls to avoid and questionable behavior to expect from other implementers.

Other White Papers

Emerging Ethernet Protocols (compares IDA, EIP, ProfiNet, MB/TCP etc)