Teledyne 2101 installation and operation guide Modbus Ascii Address 1 Register Definitions

2101 Field Wizard

Section 4 Modbus Protocol

4.6Register Specifications All numbers in the Modbus registers are stored most significant byte first. If the polling device has a byte ordering of least signif- icant byte first (an Intel-based PC, for example), the bytes will need to be reversed after they are received.

The Modbus ASCII address is used to index the data by modules.

Modbus ASCII address 1 contains information related to the site. The first register contains a 16-bit integer count of the number of modules that have data to report. The maximum number of modules that can be supported is 4.

Modbus ASCII addresses 2 through the number of modules plus 1 contain data from the individual modules.

The Modbus ASCII addresses will be sorted by the model number, and then by module name, which is entered by the user through Flowlink. This allows the user to control the ordering of the addresses and easily predict what data will be in specific reg- isters.

Every measured parameter has a corresponding status and mea- surement time that are updated with each measurement.

The maximum number of supported measurements from all modules in the system is 28.

The Modbus registers are assigned within 30 seconds after the 2100 module is powered up. To conserve power for the users who do not use Modbus communications, no Modbus registers will be updated with sensor readings until a Modbus master communi- cates with the 2100 module.

The register definitions for the Site Information device (Modbus

ASCII address 1) are in Table 4-1below:

Table 4-1 Modbus ASCII Address 1 Register Definitions

Register	Name	Data type	Units	Read/Write
Number(s)
1	Number of	16 bit integer	None	Read
	modules (N)
	(1-4)
2-20	Site name	38-byte string	None	Read

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