Automobile Parts - Air Flow Meter User Manual

Series 24-HP Instruction Manual Appendix E MODBUS Commands

IM-24-HP E-5

The following registers contain the display units strings:

Registers Variable Data type Units Function code Addresses

32007-32012 Volume flow units string — 03, 04 2006-2011

32001-32006 Mass flow units string — 03, 04 2000-2005

32025-32030 Temperature units string — 03, 04 2024-2029

32019-32024 Pressure units string

—

03, 04 2018-2023

32031-32036 Density units string — 03, 04 2030-2035

32013-32017 Energy flow units string — 03, 04 2012-2017

Function codes 03 (read holding registers) and 04 (read input regis-

ters) are the only codes supported for reading these registers, and

function codes for writing holding registers are not implemented.

We recommend that the floating point and long integer registers be

read in a single operation with the number of registers being a mul-

tiple of two. If these data are read in two separate operations, each

reading a single 16-bit register, then the value will likely be invalid.

The floating point registers with values in display units are scaled

to the same units as are displayed, but are instantaneous values

that are not smoothed. If display smoothing is enabled (non-zero

value entered in the Display TC item in the Display Menu), then

the register values will not agree exactly with the displayed val-

ues.

Exception Status Definitions

The Read Exception Status command (function code 07) returns the exception

status byte, which is defined as follows. This byte may be cleared by setting “coil”

Bit(s) Definition

0-1 Byte order (see Modbus Order on page 2)

0 = 3-2:1-0 1 = 2-3:0-1

2 = 1-0:3-2 3 = 0-1:2-3

2 Temperature sensor fault

3 Pressure sensor fault

4 A/D converter fault

5 Period overflow

6 Pulse overflow

7 Configuration changed