Dwyer Instruments UFM2 - Modbus Error Messages (if Modbus Fitted); Flow Errors; Flow Warnings

UFM2/UBT User Manual
Issue 1.1b July 20 Page 39
6.5.3 Modbus Error Messages (if Modbus fitted)
Test case
Transmitter
Address
Command
Start Register
Length
(no of registers)
CRC-16
[1 byte]
[1 byte]
[2 bytes]
[2 bytes]
[2 bytes]
No error
0x01
0x03
0x00
0x00
0x00
0x20
0x44
0x12
Incorrect function
request
0x01
0x0C
0x00
0x00
0x00
0x20
0x10
0x13
incorrect register
start
0x01
0x03
0x00
0xEF
0x00
0x20
0x75
0xE7
Incorrect register
length
0x01
0x03
0x00
0x12
0xFF
0x02
0x25
0xFE
slave is busy
0x01
0x03
0x00
0x00
0x00
0x20
0x44
0x12
incorrect CRC-16
0x01
0x03
0x00
0x20
0x00
0x20
0x44
0xFF
Receiver
Comments
Address
Command
Error code
CRC-16
[1 byte]
[1 byte]
[1 byte]
[2 bytes]
0x01
0x03
None
n/a
n/a
Example of a good message
0x01
0x8C
0x01
0x85
0x00
ILLEGAL FUNCTION - the only acceptable
command is 0x03
0x01
0x83
0x02
0xC0
0xF1
ILLEGAL DATA ADDRESS - incorrect
register start
0x01
0x83
0x03
0x01
0x31
ILLEGAL DATA VALUE - incorrect register
length
0x01
0x83
0x06
0xC1
0x32
SLAVE DEVICE BUSY – unit is busy
processing and is unable to respond
0x01
0x83
0x07
0x00
0xF2
CRC is incorrect
6.5.4 Flow Errors
A signal strength of less than 40% indicates poor set up of the instrument, and the installation
should be checked or possibly moved to a different site.
6.5.5 Flow Warnings
A signal strength of less than 40% indicates poor set up of the instrument, and the installation
should be checked or possibly moved to a different site. A negative flow is indicated by an”!” being
displayed on the top line instead of a “*”.