Spirax Sarco VLM20 Instrucciones De Instalación Y Mantenimiento página 95

5.6.1 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" register #00003 (function code
5, address 2, data = 0xff00).
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
5.6.2 Discrete input definitions
The status of the three alarms may be monitored via the Modbus Read Discrete Input command
(function code 02). 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,
Registers
10001
10002
10003
5.6.3 Control register definitions
The only writeable 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.
IM-P339-06 MI Issue 2
Variable
Alarm #1 state
Alarm #2 state
Alarm #3 state
Function code
02
02
02
Address
0
1
2
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