Interface is a shared boundary between two or more functional units (device, PC, etc.) defined by common physical interconnection characteristics, signal characteristics and functional characteristics of the interchange circuits.

Protocol is a standardized set of rules for data transmission over a communication interface.

The communication interfaces used in industry can be of two types:

Point-to-Point. There are only one transmitter and one receiver in the network; the data is transferred only in one direction per a signal line.

Point-to-Multipoint. There is one transmitter and several receivers in the network; the data is transferred only in one direction per a signal line.

The main characteristic of any communication interface is its baud rate. This rate defines how many bits of data are sent over a line per second (bps, Mbps, etc.). Usually, the baud rate includes ‘payload’ and ‘overhead’ parts. The overhead usually encompasses the packet format or the protocol frame: source/destination bits, error checking bits, control bits, etc. The payload is the net data rate or the effective data rate. The payload differs depending on the particular interface and protocol and can make from 30% to 90% of the baud rate. This must be taken into account.

Interfaces and protocols used in akYtec devices:

Interface Type Baud rate Line length Protocol*
RS485 Point-to-Multipoint (up to 32 devices) standard 115200 bps max. 1200 m (without repeater) akYtec
Modbus ASCII
Modbus RTU
RS232 Point-to-Point max. 3 m
Ethernet 10/100 base T (twisted pair) Point-to-Point 10 Mbps / 100 Mbps max. 100 m Modbus TCP
USB 1.1 Point-to-Point 12 Mbps max. 3 m Mass Storage Device
CDC Device
USB 2.0 Point-to-Point up to 480 Mbps
*depends on the device

Device compatibility

Device compatibility refers to the ability of devices to exchange data between each other. Each of devices participating in the data exchange has to be equipped with a certain interface and support a certain protocol. But even in this case, the ability for data exchange isn’t always possible since one device may not be able to send the information the other one is supposed to receive. The question is therefore what to do if the devices support the same data type but feature different interfaces and/or support different protocols? It is required to use interface adapters or protocol translation gateways.

Interface adapter is a device with two or more interfaces which retransmits data from one interface into others. However, information transmission is carried out without its conversion. It means the devices connected through an interface adapter should support same protocols.

Protocol transmission gateway (or protocol converter) is a device which is intended to convert data of one protocol into the other one. At the same time, a protocol converter can also serve as an interface adapter as well. But unlike an interface adapter, the protocol converter requires configuring for specifying what data via what protocols are supposed to be transferred in the communication network.

Read more information in our post 'Interfaces and protocols used in akYtec products – Part 2'.