Catalyst Data Register; What Is An Sna; Sna Data Types; Sna Discrete And Analog Register Addressing - Raco Catalyst Owner's Manual

C. Catalyst Data Register SNA Addressing
It is helpful to have a basic understanding of the Catalyst addressing system to
configure alarms successfully.

What is an SNA?

The PLC sends alarm data to the Catalyst via the Catalyst Ethernet Module's IP
address in conjunction with a unique SNA (System Net Address) address. The SNA
consists of a Network number, a Node number, and an address on that node. SNA
1*2*00001 would identify Network 1, Node 2, Address 00001. For the Catalyst
Ethernet Module, the Network is always 1 and the Node is always 2: 1*2*xxxxx.
The Catalyst can read 1968 addresses in the range from 1*2*00001 to 1*2*01968.
Each of those addresses corresponds to one bit (coil). Any of these addresses can be
assigned to any Catalyst alarm channel. This also can be represented as a range of
123 16-bit analog addresses in the range of 1*2*40001 to 1*2*40123. The relationship
between discrete and analog addressing is described in the following sections.

SNA Data Types

The Catalyst determines if the SNA represents discrete or analog data by the first digit
of the SNA. If the first digit is a 0 (1*2*00001) then the data is a single discrete bit.
This can be considered as the equivalent of a PLC coil. If the first digit is a 4
(1*2*40001) then the data is a 16-bit integer register that represents an analog
reading like pressure or temperature.

SNA Discrete and Analog Register Addressing

This SNA numbering convention is just two different ways of looking at the same data
registers. The 16-bit register at 1*2*40001 is composed of the 16 single bit registers
1*2*00001 to 1*2*00016. In other words, SNA 1*2*00001 refers to a bit in the 16-bit
register 1*2*40001. SNA 1*2*000016 would be another bit in the SNA 1*2*40001
register. SNA 1*2*000017 would be a bit in the SNA 1*2*40002 register. The exact
mapping is covered in Section 2.C.e.
For simplicity in avoiding conflicts, we suggest that you assign the Discrete channels
Saved: 2015-08-03
Filename:
Catalyst EtherNet Option Setup R5 V01.docx
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