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Chapter 4. Serial Communications
90 PanaFlow™ MV80 & MV82 User’s Manual
4.2.6g Exception Status Definitions
The Read Exception Status command (function code 07) returns the exception status byte, which is defined as shown in
Table 11 below. This byte may be cleared by setting “coil” register #00003 (function code 5, address 2, data = 0xff00).
4.2.6h Discrete Input Definitions
The status of the three alarms may be monitored via the Modbus Read Discrete Input command (function code 02), as
shown in
Table 12 below. The value returned indicates the state of the alarm, and will be 1 only if the alarm is enabled
and active. A zero value is transmitted for alarms that are either disabled or inactive.
4.2.6i Control Register Definitions
The only writable registers in this implementation are the Reset Exception Status, Reset Meter and Reset Totalizer
functions, which are implemented as “coils” which may be written with the Write Single Coil command (function code
05) to address 8 through 10, respectively, (register #00009 through #00011). The value sent with this command must be
either 0x0000 or 0xff00, or the meter will respond with an error message; the totalizer will be reset or exception status
cleared only with a value of 0xff00.
Table 11: Exception Status BIts
Bit(s) Definition
0-1 Byte order (see Modbus Order on “Modbus Order” on page 86 )
•
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
Table 12: Alarm Status Registers
Registers Variable Function Code Address
10001 Alarm #1 state 02 0
10002 Alarm #2 state 02 1
10003 Alarm #3 state 02 2