The International Electrotechnical Commission standard 870 part 5 (IEC 870-5) is a set of transmission procedures intended for SCADA systems. The publication got reissued with a designation in the 60000 series as of the year 1997. Refer to IEC 60870-5-101 for serial communication, and IEC 60870-5-104 for the TCP-based evolution. The two are commonly abbreviated as IEC 101 and IEC 104 respectively.

The project consists of a Go library and a command-line tool called iecat(8).

This is free and unencumbered software released into the public domain.

At its essence, part 5 formalizes reliable means to exchange measurements and commands. Commands are used by controlling stations to cause a change of state in operational equipment. Controlled stations may then optionally either confirm or or reject the execution. Controlled stations can also optionally indicate completion with a terminate.

Controlling stations are called primary and the controlled stations are called secondary. With unbalanced transmission one station is primary and the other is secodary, a.k.a. master/slave, and with balanced transmission stations can both act as primary and as secondory, a.k.a. peer to peer.

Every information object address resides in a common address. Primaries may acquire the information present in a common address with an interrogation command. E.g., run iecat -host station1.example.com -inro 42 to aquire a listing of common address 42 on the terminal.

The following is not implement yet.

• file transfer, type identifier F_*
• parameter of measured value, type identifeir P_*

Run go install github.com/pascaldekloe/part5/cmd/iecat@latest to build the command into the bin directory of go env GOPATH.