Emerson Micro Motion 3711, Руководство по конфигурации и использованию, Страница: 155 / 234

Configuration and Use Manual 147
Modbus Interface
PID Contr
o
l Loops
Mo
db
us I
n
terface
Fu
ncti
o
n
Sequ
en
ce T
a
b
le
s
Monitoring and Displa
ys
PID Contr
o
l Loops
Mo
db
us I
n
terface
Fu
ncti
o
n
Sequ
en
ce T
a
b
le
s
Monitoring and Displa
ys
PID Contr
o
l Loops
Mo
db
us I
n
terface
Fu
ncti
o
n
Sequ
en
ce T
a
b
le
s
Monitoring and Displa
ys
PID Contr
o
l Loops
Mo
db
us I
n
terface
Fu
ncti
o
n
Sequ
en
ce T
a
b
le
s
Monitoring and Displa
ys
A maximum of twelve records can be returned in one reply. Records are collected until there are no
more unacknowledged records or until the maximum record number is reached, whichever occurs
first.
To access event and alarm logs, a Modbus host program must perform these steps:
1. Send a function code 03 request referencing register 32 (see Table 12-8).
2. Read and interpret the reply. The maximum number of bytes that can be returned is 240
(twelve 20-byte records). See Table 12-9 for the structure of the data field in event log records
and alarm log records. The structure of bytes 1 and 2 in the data field is described in
Table 12-10.
3. Send a function code 05 request referencing register 32 (see Table 12-8) to acknowledge all
records returned in the preceding response.
Note: If events and alarms are not acknowledged, they will be returned in the next response to an
alarm or event log request.
Table 12-8 Modbus event and alarm data requests
Modbus
function code
Data field
Description Register bytes Data bytes
03 32
(1)
(1) Default register. Register number may be changed in History Access Registers panel.
N/A Requests unacknowledged event and alarm
records.
05 32
(1)
N/A Acknowledges all records returned in the
preceding response.
Table 12-9 Data field structure for event records and alarm log records
Byte
Data field
Event log record Alarm log record
1-2 Operator change (Event Log) bit map (16-bit integer).
Refer to Table 12-10. Alarm change bit map (16-bit integer).
Refer to Table 12-10.
3-4 Modbus register number of variable (16-bit integer) Modbus register number of variable (16-bit integer)
5-8 Timestamp (HHMMSS; 32-bit floating point) Timestamp (HHMMSS; 32-bit floating point)
9-12 Datestamp (MMDDYY; 32-bit floating point)
(1)
(1) Calculated as years since 1980. For example, for 2005 the YY value is 25. Note that this is different from the YY value in history data.
Datestamp (MMDDYY; 32-bit floating point)
(1)
13-16 Previous value of variable (32-bit floating point) Current (alarmed) value of variable (32-bit floating
point)
17-20 Current (new) value of variable (32-bit floating point) Unused (zero filled when transmitted to the master)
Table 12-10 Operator change and alarm change bit maps
Bit Operator change bit map Alarm change bit map
0 Fixed value – Change to an EU value on an I/O point in Manual Mode Not used
1 Zero scale – Change to the 0% Adjusted on an AO or AI Not used
2 Full scale – Change to the 100% Adjusted on an AO or AI Not used
3 Operator entry work value – Change to any parameter other than
those described above Not used