Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 215)

Publication AG-UM008C-EN-P - February 2005
Configuring MicroLogix 1000 Controllers 6-11
Table 6.1 DF1 Half-duplex Slave Configuration Parameters
Configuring RTS Send
Delay and RTS Off Delay Through your programming software, the parameters RTS Send Delay
and RTS Off Delay give you the ability to set how long RTS is on prior
to transmission, as well as how long to keep it on after transmission is
complete. These parameters only apply when you select half-duplex
modem. For maximum communication throughput, leave these
parameters at zero.
For use with half-duplex modems that require extra time to
turnaround or key-up their transmitter even after they have activated
CTS, the RTS Send Delay specifies (in 5 millisecond increments) the
Parameter Description Default
Baud Rate Toggles between the communication rate of 300, 600, 1200, 2400, 4800, 9600, 19200, and
38.4K. 9600
Node Address Valid range is 0 to 254 decimal. 1
Control Line Toggles between No Handshaking and Half-duplex Modem. No Handshaking
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 will be deactivated. Gives modem extra time to transmit the last character of a
packet. The valid range is 0 to 255 and can be set in increments of 5 ms. Refer to page 6-11 for
further details. 0
RTS Send Delay Specifies the time delay between setting RTS until checking for the CTS response. For use
with modems that are not ready to respond with CTS immediately upon receipt of RTS. The
valid range is 0 to 255 and can be set in increments of 5 ms. Refer to page 6-11 for further
details. 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 will wait for a poll from the master device. If the slave device does
not receive a poll within the Poll Timeout, a MSG instruction error will be generated, and the
ladder program will need to requeue the MSG instruction. The valid range is 0 to 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 0 not be used. Poll Timeout is disabled if set to 0. Refer to page 6-12 for
further details. 3000
(60 seconds)
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 to 255 and can be set in increments of 5 ms. 0
Message Retries Specifies the number of times a slave device will attempt 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 to 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