KROHNE ALTOSONIC V Modbus EN - Manual (Page 25)

ALTOSONIC V
ModBus Manual 0300 rev07 E 7.30855.35.00 Page 25 of 64
7.4 What can go wrong?
When using RS485, check:
•
Are the connections between terminal 1 and 4 made?
•
Are the connections between terminal 2 and 3 made?
• Is the terminate resistor placed between 1+4 and 2+3 (only if UFP-V is the end of the line).
• Is the jumper set to 485 and not 422? (else the transmitter will continuously be activated and
destroy received messages)
•
Is the polarity correct? Are the lines by accident swapped?
• Is the software set to Half Duplex (3.8 MODBUS_UART_HALF_DUPLEX=1)
When using RS422, check:
•
Are both terminator resistors placed at the end of the cable on the TX+, TX- and RX+, RX- lines?
•
Is the jumper on the RS485 card set to 422?
•
Is the software set to Full duplex ((3.8 MODBUS_UART_HALF_DUPLEX=0)?
Other checks:
•
Are the following items correct:
baud rate (3.3 MODBUS_UART_BAUDRATE)
N stop bits (3.6 MODBUS_UART_N_STOPBITS)
parity
(3.7 MODBUS_UART_PARITY)
•
Are both systems in the same mode RTU/ASCII (ASV system = 3.9
MODBUS_TRANSFER_MODE)?
•
Is the Slave ID (5.3 MODBUS_SLAVE_ID) correct?
•
Notice that RTU requires precise timing specifications, some of the RS485 -> RS232/422
converters perform data buffering and may give problems.
If this is the problem try the ASCII mode (3.9 MODBUS_TRANSFER_MODE).
• Notice that the Slave device will not give any response when it is addressed with a broadcast
(SlaveID=0).
Extra information:
The UFP-V has extra windows, which provide information about the Modbus communication:
These windows are accessed from the Main Window by function key F10
See also Altosonic-V Operating Manual (chapter RUNTIME WINDOWS)
7.5 How Status Flags are Updated
If the status flags must be self-resetting
Each machine cycle (35 ms) all the error and warning flags are updated with the last machine status.
An active flag will be pending for at least (5.4 FLAG_HOLD_TIME * 35) ms.
An Active Flag may be reset earlier (by writing a zero) than the pending time (5.4 FLAG_HOLD_TIME
* 35 ms), but the next update will be after the pending time.
If the flags must be acknowledged
To activate this mode, the parameter 5.4 FLAG_HOLD_TIME must be set to 0. Each machine cycle
(35 ms) all warning and error flags are updated with the last machine status.
The flags can be reset by:
•
writing a 0 to these flags or
•
writing a 1 to the accompanying acknowledge flag (each status flag has an accompanying
acknowledge flag) or
• writing a 1 to the acknowledge_all flag
(for host computers with limited free programmable Boolean space).