IEC 104 - IEC 60870-5-104
IEC 60870-5 is a protocol standard for telecontrol, tele-protection, and other telecommunication functions for electric power systems.
IEC 60870-5-104 (short IEC-104) is a companion standard defining how to extend the IEC 60870-5-101 protocol to gain network access using standard transport profiles.
IEC 60870-5-101 (IEC101) is a standard for power system monitoring, control and other related communications to automate electric power systems.
IEC 60870-5-104 (IEC104) is an extension of the IEC 101 protocol, including transport, network, link & physical layer extensions to enable a full network access.
For communications within Ethernet LANs (Local Area Networks) the data is channeled through TCP/ IP.
Two seperate link layers enable data transfer over of both Ethernet & serial media (PPP - Point-to-Point Protocol).
IEC 104 contains various types of mechanisms to synchronize data in networks effectively.
IEC 104 vs 101
The IEC 60870-5-101 (short IEC-101) and IEC 60870-5-104 (short IEC-104) protocols are both used to transmit SCADA data in electric power systems. While IEC-104 uses data packets to transmit data via TCP/IP, IEC-101 is uses serial data communications (e.g. based on RS-232 and FSK interfaces) for transmission.
IEC 104 vs DNP3 DNP3 and IEC-104 have both been specifically developed for SCADA communication beyond the substation level, for instance in order to control a circuit breaker from a Control center.
However, there are a few advantages of DNP3 that make it superior in certain applications.
For the transmission of larger data volumes over longer distances, DNP3 is preferred as it sends larger but fewer data packages than IEC-104, which sends a high number of small packages.
DNP3 also enables faster data transmission by operating in higher baud rates (number of data bits transmitted in one second) than the IEC standards. At last, if the bandwidth is limited, DNP3’s data priority classes (Class 1,2,3) allow the controller to poll in various frequencies, as opposed to IEC-104, which only provides a constant polling frequency.
IEC 104 vs IEC 61850
Although both IEC standards define communication technology for the remote control and automation of electrical systems, there are several reasons that explain why it does not make much sense to oppose to the two standards.
IEC 61850 is actually a multidimensional standard comprising protocols and data models, as it not only defines how data is sent and received but also describes how data is executed and stored.
IEC 104 is a common protocol based on the OSI reference model, whereas IEC-61850 is often used for data mapping of standard protocols such as DLMS, DNP3 or IEC-101/102/103/104 in order to take advantage of the efficient data transfer and execution of IEC 61850.