Rockwell Automation 1770-KF3 DH-485 Communication Interface User Manual - Manual (Page 31)

Configuring the KF3
Chapter 3
3Ć8
Table 3.C
Submenu Configuration Parameters
Parameter Number Parameter Description Factory Default
Maximum Token
Holder
The node address of the highestĆnumbered master station on the Address
DHĆ485 link. The valid range for Maximum Token Holder is 01Ć31.
If all stations have consecutive addresses, this parameter should be set
to the address of the highestĆnumbered master station on the link. For
example: if there are 5 stations, addressed 0 to 4, this parameter should
be set to 04.
This improves the token rotation time (the time it takes for the token to
go once around the network) by limiting the station solicitation that is
required, but only when all stations have consecutive addresses
starting at zero. If gaps exist in the station addresses, setting this
parameter to the highest station address will have no effect on link
performance.
Note that setting this parameter to the highest station address will not
allow new stations above that address onto the network. Their addresses
would be above the maximum token holder address, and therefore they
would never be solicited to join. Stations with addresses higher than the
maximum token holder address value are not solicited to join the network,
but are removed from the network. If you want to add new stations, you
must reset this parameter to a higher value.
The KF3 will not allow you to set this value to less than its current station
address.
(31).
Token Hold Factor The number of message that this station is allowed to send on the DHĆ485
link while it has the token. The valid range is 01Ć10.
Consider carefully before changing this parameter. Setting all stations to
a value of 01 gives all stations on the network equal access to the link,
and does not allow any one station to affect the performance of other
stations. Increasing this value for one station allows that station to hold
the token longer if it has more than one message to send. This improves
the performance of that station, but at the expense of the other stations on
the network.
(01).
Number of Retries The number of allowable retries on the RSĆ232C link. Valid numbers are
00 (no retries per attempt) to 10 (10 retries per attempt).
2 retries per attempt
(02).
DF1 ACK Timeout The time to wait for an ACK to be received from the host computer. The
timeout is from 0.1 to 5 seconds in 0.1 second increments. To calculate
the timeout, multiply the number in the display by 0.1 seconds.
For example: A setting of 14 means 14 x 0.1 = 1.4 seconds.
1 second (10).