Modbus Rtu Cable Specification

Modbus is a data communications protocol originally published by modicon now schneider electric in 1979 for use with its programmable logic controllers plcs.

Modbus rtu cable specification.

1200 m or more are possible. If you agree to the terms herein then you must click the i accept button below before you are permitted to use this software protocol and related documents. This document comes in complement to the document called modbus application protocol specification. Modbus is popular in industrial environments because it is openly published and royalty free.

Of slaves also depend on the data logger specification. General overview of modbus documents. Under ideal conditions cable lengths of 4000 ft. Typesp50is a iec ipc620systemi o 9271 twinax 25awg 124ohm.

Modbus cable interface quickly and easily with most existing plant control architectures by using belden cabling for modbus. In chapter 5 different implementation classes are defined for modbus serial line. Networks system sds honeywell access4000system 9248 rg 6pvc foundationfieldbus se eprotocollistingsonpage4. Please review the following license agreement before down loading any modbus protocol or related documents from this web site.

However the cable recommended for long lengths can be expensive so if there is an existing ethernet infrastructure in place it may be more affordable to convert from bacnet ms tp or modbus rtu over rs 485 to bacnet tcp ip or modbus tcp ip over ethernet. The modbus rtu specification is respected in the physical and data link layers. The maximum length of the communication cable should be no longer than 800m recommended the maximum number of devices that can be connected over this network can be 32 for modbus rtu including the master device trackso data logger in our case apart from the network no. Modbus has been a standard for interfacing remote i o and plcs into the process dlc system for over 20 years allowing most legacy control systems to interface easily with modbus.

Go back to modbus rs485 cabling rules 8. Specification of a class is the sum of requirements that a device must respect in order to belong to that class. Modbus has become a de facto standard communication protocol and is now a commonly available means of connecting industrial electronic devices. The message structure of the modbus rtu function codes is employed and standard ieee 32 bit floating point and integer formats are used.

In order to avoid signal reflections a 120 ohm termination resistance must be fitted on each end of. The definition in table 2 1 is the register mapping for many honeywell. Modbus specifications and implementation guides.