Vaisala HMT330 - Manual (Page 206)

User's Guide _______________________________________________________________________
204 __________________________________________________________________ M210566EN-K
Other configuration settings are not usually needed and are not available
using the Modbus interface. The service cable must be used to change
other configuration settings if needed.
Exception Status Outputs
Exception status outputs (read with function code 07) tell the summary of
the HMT330 transmitter status as described in Table 45 below.
Table 45 HMT330 Exception Status Outputs
Output Name Description
0 (0x01) Fault status 1 = No errors
1 (0x02) Online status 1 = Online data available
Status information is available also with register access; see section
Status Registers (Read-Only) on page 202.
Diagnostic Sub-Functions
HMT330 supports some of the Modbus diagnostic functions described in
the Modbus Application Protocol Specification V1.1b. These diagnostic
functions are accessed with function code 08. See Table 46 below for
details.
Table 46 HMT330 Modbus Diagnostics
Code Sub-Function Name Notes
00 (0x00) Return Query Data
01 (0x01) Restart Communications
Option Cancels the “Listen Only” mode.
Data field must be set to “00 00”
for Restart Communications
Option. Sub-Function 01 with
data field “FF 00” is rejected.
02 (0x02) Return Diagnostic Register Non-zero if there are active
transmitter errors.
For same error information, see
status registers 0516 and 0517.
The value of the Diagnostic
Register is a logical OR of these
two status registers.
04 (0x04) Force Listen Only Mode Puts device “off-line”
10 (0x0A) Clear Counters and
Diagnostic Register Diagnostic Register cannot be
cleared
11 (0x0B) Return Bus Message Count Total number of messages seen
on the bus/interface
12 (0x0C) Return Bus Communication
Error Count Number of messages with bad
Modbus RTU CRC or Modbus
TCP frame