Rockwell Automation 1747-KE,D17476.12 DH-485/RS-232C Interface Module - Manual (Page 63)

Publication 1747-UM005B-EN-P - March 2006
Module Configuration Using an ASCII Terminal 5-9
DF1 Full-duplex Setup Parameters
When the module is powered up for the first time, the DF1 protocol
will be set to the default parameters. If these parameters are changed
and the setup is saved, then the module will always power up with
the new settings, unless the battery fails and power to the module’s
RAM is lost.
DF1 Full-duplex Setup Parameters
Parameter Default Options Description
Duplicate Packet
Detection Disabled Enabled, Disabled Determines whether duplicate message detection is
Disabled or Enabled. When enabled, duplicate
messages will be acknowledged and discarded.
Checksum BCC BCC, CRC16 Determines the type of error detection that will be
used on the DF1 link. It must be the same as that for
any application programs that may be running.
Constant Carrier Detect Disabled Disabled, Enabled If enabled, hardware handshaking is forced on. The
module will monitor the carrier from the modem (DCD
signal) and will not begin communication until it is
detected.
Modem Init String (blank) Lets you configure your modem using Hayes
commands upon every power cycle of the module. For
example, entering ATDT here would get the modem’s
attention (AT) and set it to tone dialing (DT). Sending a
(~) character will produce a 1 s wait on the modem.
Refer to your modem user manual for details.
Modem Init String Delay 0 s 0...25 s Determines the amount of time the module will wait
before sending the Modem Init String to the modem.
Message Timeout 10,000 ms 100...12,750 ms The time to wait for a response to a message sent on a
DF1 network. This parameter is rounded down to the
nearest 50 ms increment. For example, if you enter 199
ms, it is accepted as 150 ms.
Hardware Handshaking Disabled Disabled, Enabled If enabled, the module will use the RTS and CTS
signals for control of the modem.
Embedded Response
Detect Embedded
Response Embedded
Response,
Auto Detect
Embedded Response Selecting Embedded Response lets the module to send
embedded responses within packets. Selecting Auto
Detect Embedded Response causes the module to use
embedded responses only if an embedded response
from the host is received by the module.
ACK Timeout 200 x 5 ms (0...65,535) x 5 ms Determines the time the module will wait for an ACK
to be received from the host DF1 device.
ENQuiry Retries 2 0...254 Determines the number of enquiry retries that will be
attempted before a packet transmission is considered
to have failed.
NAK Received Retries 2 0...254 Determines the number of packet retries that will be
attempted when NAK responses are received on
previous transmissions of the packet.