Status Registers

Overview

This section describes the function and parameters of the module status block and the ASCII header block.

Module Status Block Function

These registers provide information about the module's revision level and current operating parameters.

Module Status Block Parameters

The module status block layout is described in the table below. The registers can be read, but cannot be written into.

Reference (hex)	Purpose	Contents
4F801	Length of status block (words)	12 decimal
4F802	I/O module quantity of input bytes	Module dependent
4F803	I/O module quantity of output bytes	Module dependent
4F804	I/O module ID number	Module dependent
4F805	I/O module revision number	Format: XRwhere:X = upper 4 bits, always 0000R = lower 12 bits, defining the revision as 3 hex characters.Example: 100 hex = Rev. 1.00 200 hex = Rev. 2.00
4F806	ASCII header block length (words)	Module dependent
4F807	Last node address to communicate	1...64 decimal
4F808	Remaining ownership reservation time	30...6000 decimal, in units of 10 ms (300 ms...60 s)
4F809	Remaining outputs holdup time	30...6000 decimal, in units of 10 ms (300 ms...60 s)
4F80A	I/O module health	8000 hex = healthy0000 hex = not healthy
4F80B	I/O module last error value	Module dependent
4F80B	I/O module error counter	Error count 0000...FFFF hex

ASCII Header Block Function

These registers contain an ASCII text description of the module.

ASCII Header Block Parameters

The block length depends upon the type of I/O base to which the adapter is connected. The maximum length is 64 bytes of ASCII characters, corresponding to a length of 8...32 words as specified in word 6 of the module status block (at reference 4F806).

The registers can be read, but cannot be written into.

The following table shows the header block layout as a string of ASCII characters as they are positioned from the starting reference 4FC01.

4FC01+Byte Offset	ASCIICharacters	Meaning
0...10	MODBUS PLUS	Modbus Plus network device
11	20 hex (32 decimal)	space
12	20 hex (32 decimal)	space
13 14 15	IEC	IEC data mode (Data bit order per IEC standard)
16	20 hex (32 decimal)	space
17 18 19	DIGEXPANA	Digital module (ID range: XX00...XX7F hex)Expert module (ID range: XX80...XXBF hex)Analog module (ID range: XXC0...XXFE hex)
20 21	HHLL	Module ID code(HH = high byte, LL = low byte)
22 23	I I OO	Module I/O words(I I = input words, OO = output words)
24...63	--	Reserved

Examples of an ASCII Header Block

The figure below shows two examples of an ASCII Header Block.