Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 196)

Publication AG-UM008C-EN-P - February 2005
5-10 Configuring SLC 500 Processors with 1747-KE Interface Modules
Save the Configuration
To save the configuration, follow these steps:
1. To save the configurations and exit from the menus, type X .
2. Remove power from the SLC chassis; disconnect the ASCII
terminal.
Parameter Selections
Duplicate Packet Detection Duplicate Packet Detection lets the interface module detect if it has received a message that is a
duplicate of its most recent message from the master station. If you choose duplicate packet detection,
the processor will acknowledge (ACK) the message but will not act on it since it has already performed
the message’s task when it received the command from the first message.
If you want to detect duplicate packets and discard them, choose Enable. If you want to accept
duplicate packets, choose Disable.
Checksum With this selection, you choose the how the interface module checks the accuracy of each DF1 packet
transmission.
BCC: This algorithm provides a medium level of data security. It cannot detect:
•
transposition of bytes during transmission of a packet
•
the insertion or deletion of data values of zero within a packet
CRC: This algorithm provides a higher level of data security.
Select a method that all your devices on the network can use.
When possible, choose CRC.
Constant Carrier Detect If you want the interface module to monitor the carrier from the modem (DCD signal), choose Enabled.
The module will not begin communication until the carrier is detected.
If the local modem does not normally receive a constant carrier from the remote modem, choose
Disabled.
Modem Init String Enter an ASCII string to configure your modem by using Hayes commands upon every power cycle of the
interface module.
Embedded Response Detect To use embedded responses, choose Enabled. If you want the processor to use embedded responses
only when it detects embedded responses from another device, choose Auto-detect.
If you are communicating with another Allen-Bradley device, choose Enabled. Embedded responses
increase network traffic efficiency.
ACK Timeout The amount of time, in 5 millisecond increments, that you want the processor to wait for an
acknowledgment to the message it has sent before sending an enquiry (ENQ) for the reply.
ENQuiry Retries The number of enquiries (ENQs) that you want the processor to send after an ACK timeout occurs.
NAK Receive Retries The number of times the processor will re-send a message packet because it received a NAK response
to the previous message packet transmission.