Modbus is an open protocol, meaning that it’s free for manufacturers to build into their equipment without having to pay royalties. It has become a very common protocol used widely by many manufacturers throughout many industries. Modbus is typically used to transmit signals from instrumentation and control devices back to a main controller or data gathering system.
Modbus is transmitted over serial lines between devices. The simplest setup would be a single serial cable connecting the serial ports on two devices, a Master and a Slave.
Yes. The terminator resistors indicate the beginning and the end of the LAN. So it is imperative terminator resistors (120 ohm) have to be fitted. The last Meter on the LAN and the Horizon or management system (see brochure HC1).
No. Each meter must have its own unique address (1-255)
The maximum length of cable on each LAN should not exceed 1Km
Please see the appropriate brochure for the product
We strongly recommend buying our test package if you are doing any testing with Modbus and Autometers products, the price is only £150 pounds and it can save you a lot of time. The package consists of, PC software package program (on disc) and RS 485 Converter and lead.
The package consists of, PC software package program (on disc) and RS 485 Converter and lead
The software package shows you how to send a command together with the request string, you will then get a reply from the meter (a response string) showing you how you must construct your software to read the meters successfully.
Part Number: AMS SOFTWARE and RS485 Mev Converter
You should use Beldon 9841 (2core) or Beldon 9842 (4 core)
The standard protocol setting for Autometers products are 2 wires, baud rate 9600, RTU, Floating point, High word first and parity even. The products have been designed so you can adjust to new settings such as different baud rates and different speeds this information is available in the hand book provided with the product.
If you are having difficulties in reading all or some of the meters connected to the LAN, start by connecting the first one and prove that you can communicate properly. Then keep adding one meter at a time until you can read all the meters satisfactorily.
