Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 431)

Appendix D
Understanding the Communication Protocols
D–5
DF1 Half-Duplex Slave Configuration Parameters
When the system mode driver is DF1 half-duplex slave the following
parameters can be viewed and changed only when the programming software
is online with the processor. The DF1 half-duplex slave parameters are not
stored as part of the controller downloadable image (with the exception of the
baud rate and node address). If a failed MicroLogix 1000 controller is
replaced and the backed-up controller image is downloaded to the
replacement controller, these parameters remain at default until manually
changed. Therefore, be sure to fully document any non-default settings to
the DF1 half-duplex slave configuration parameters.
Parameter Description Default
Baud Rate
Toggles between the communication rate of 300, 600, 1200, 2400,
4800, 9600, 19,200, and 38.4K.
9600
Node Address Valid range is 0–254 decimal. 1
Control Line Toggles between No Handshaking and Half-Duplex Modem.
No Hand-
shaking
Duplicate
Packet
Detection
Detects and eliminates duplicate responses to a message. Duplicate
packets may be sent under “noisy” communication conditions when the
sender’s retries are not set to 0. Toggles between Enabled and
Disabled.
Enabled
Error Detection Toggles between CRC and BCC. CRC
RTS Off Delay
Specifies the delay time between when the last serial character is sent
to the modem and when RTS is deactivated. Gives modem extra time
to transmit the last character of a packet. The valid range is 0–255 and
can be set in increments of 5 ms.
0
RTS Send Delay
Specifies the time delay between setting RTS (request to send) until
checking for the CTS (clear to send) response. For use with modems
that are not ready to respond with CTS immediately upon receipt of
RTS. The valid range is 0–255 and can be set in increments of 5 ms.
0
Poll Timeout
Poll Timeout only applies when a slave device initiates a MSG
instruction. It is the amount of time that the slave device waits for a poll
from the master device. If the slave device does not receive a poll
within the Poll Timeout, a MSG instruction error is generated and the
ladder program needs to requeue the MSG instruction. The valid range
is 0–65535 and can be set in increments of 20 ms. If you are using a
MSG instruction, it is recommended that a Poll Timeout value of zero
not be used. Poll Timeout is disabled if set to zero.
3000 (60s)
Pre-send Time
Delay
Delay time before transmission. Required for 1761-NET-AIC physical
half-duplex networks. The 1761-NET-AIC needs delay time to change
from transmit to receive mode. The valid range is 0–255 and can be
set in increments of 5 ms.
0
Message
Retries
Specifies the number of times a slave device attempts to resend a
message packet when it does not receive an ACK from the master
device. For use in noisy environments where message packets may
become corrupted in transmission. The valid range is 0–255.
3
EOT
Suppression
Slave does not respond when polled if no message is queued. Saves
modem transmission power when there is no message to transmit.
Toggles between Yes and No.
No