Modbus Frequently Asked Questions (FAQ) and Answers

Chipkin has Modbus solutions for almost every situation. We are experts in Modbus RTU/TCP communication and carry a wide variety of Modbus products:

Frequently Asked Questions (FAQ)

Modbus TCP

What type of protocol is Modbus TCP?

Modbus TCP supports various Modbus functions and data types and scaling/bit packing can also be applied…

What is the minimum subset of function that a Modbus salve device should implement?

It depend on if you are creating a commercially available slave device or your own slave device. If you are creating a Modbus Slave device that will only be interrogate by a specific Modbus Master, then you only …Read about minimum subset of function

We want to check the communication between our device and personal computer, so we need the 232 communication software?

There are a few free utilities to check communications between your PC and your Modbus device. Try searching Google for Free Modbus Slave utilities…Read more

Modbus to Modbus – A Simple Way to Convert Serial (RTU) to TCP/IP and TCP/IP to Serial (RTU)

In an assembly where the Fieldserver device is reading from a Modbus device on Modbus RTU (Serial) or Modbus TCP/IP (Ethernet), and then serving to another Modbus device on Modbus TCP/IP or Modbus RTU, i.e., if the Fieldserver is integrating from Modbus to Modbus – RTU to TCP/IP or TCP/IP to RTU, then…visit page A Simple Way to Convert Serial (RTU) to TCP/IP and TCP/IP to Serial

This example FieldServer configuration illustrates a config which reads data from a Modbus/TCP device and makes the data available as BACnet data. A remote BACnet client can read and write points. Relationship between a connection, node and Map Descriptor for a client The name of the connection/adapter…>

Introduction Digitrip 3000 Protective Relays are manufactured by Cutler-Hammer (Eaton Corporation). Typically, Modbus TCP registers are provided as control registers for these Digitrip 3000 Protective Relays in the Digitrip 3000 Control documentation. It is very important to note that ALL of these…

Modbus RTU

The Modbus RTU protocol itself was designed based on devices with a 16-bit register length. Consequently, special considerations were required when implementing 32-bit data elements. This implementation settled on using two consecutive 16-bit registers to represent 32 bits of data or essentially 4 bytes of data. It is within these 4 bytes of data that single-precision floating point data can be encoded into a Modbus RTU message…

Why are 7 data bits bad for Modbus RTU?

Modbus RTU is a binary protocol. It requires the use of all 8 bits in each character / byte that forms the message because there are many situations where the 8th bit is used…

You should be able to write a Modbus client in any language that has access to the serial ports or a TCP connection. C# has access to both the serial port and a RAW TCP connection, therefore it should not be too hard to create a simple Modbus Client with C#…

If you are creating a Modbus Slave device that will only be interrogated by a specific Modbus Master, then you only have to implement the functions that the Modbus Master will use to call on your Modbus Slave.

Where can I find more Modbus developer resources?

The internet offers a wide variety of sites related to Modbus development from personal to commercial sites. One major resource site is the main Modbus website. Another great resource is our own Modbus Protocol Information page.

FieldServer provides 4 functions to convert Modbus 16 bit numbers to 32 bit numbers. These functions take two 16 bits numbers to form one 32 bit number, and each function processes the bytes in a different order…

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