Danfoss VLT 2800 Series Operating Instructions Manual page 10

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
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's Modbus RTU
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.
10
VLT® Serie 2800 and VLT® Serie 6000 Modbus RTU
j 100 ms
MG.10.S1.22 - VLT is a registered Danfoss trademark