Preface
MicroLogix 1000 Programmable Controllers User Manual
D–6
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 will
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 will be 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 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 0–65535 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 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 0–255.
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
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