Danfoss VLT 8000 AQUA Instrukcje Operacyjne Pobierz pdf (Strona 168)

VLT

8000 AQUA

Description of choice:

The output frequency of the frequency converter

can be frozen at the present value at any given

time, frozen at parameter 211 Preset reference 1,

frozen at parameter 202 Max. output frequency,

or stop and activate a cut-out.

570 Modbus parity and messag e framing

(M.BUS PAR./FRAME)

Value:

(EVEN/1 STOPBIT)

[0]

(ODD/1 STOPBIT)

[1]

✭ (NO PARITY/1 STOPBIT)

[2]

(NO PARITY/2 STOPBIT)

[3]

Function:

This parameter sets up the drive’sModbusRTU

interface to communicate properly with the master

controller. The parity (EVEN, ODD, or NO PARITY) must

be set to match the setting of the master controller.

Description of choice:

Select the parity that matches the setting for the

Modbus master controller. Even or odd parity is

sometimes used to allow a transmitted word to be

checked for errors. Because Modbus RTU uses

the more efficient CRC (Cyclic Redundancy Check)

method of checking for errors, parity checking is

seldom used in Modbus RTU networks.

571 Modbus communications timeout

(M.BUS COM.TIME.)

Value:

10 ms - 2000 ms

✭ 100 ms

Function:

This parameter determines the maximum amount

of time that the drive’s Modbus RTU will wait

between characters that are sent by the master

controller. When this amount of time expires, the

drive’s Modbus RTU interface will assume that it

has received the entire message.

Description of choice:

Generally, the value of 100 ms is sufficient for Modbus

RTU networks, although some Modbus RTU networks

may operate on a timeout value as short as 35 ms.

If this value is set too short, the drive’sModbusRTU

interface may miss a part of the message. Since the

CRC check will not be valid, the drive will ignore the

message. The resulting retransmissions of messages

will slow communications on the network.

If this value is set too long, the drive will wait longer

than necessary to determine that the message is

completed. This will delay the drive’s response to the

message and possibly cause the master controller to

time out. The resulting retransmissions of messages

will slow communications on the network.

✭ = factory setting. () = display text [] = value for use in communication via serial communication port

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