Rockwell Automation 1747-KE,D17476.12 DH-485/RS-232C Interface Module - Manual (Page 77)

Publication 1747-UM005B-EN-P - March 2006
Module Configuration Using the Backplane 6-11
DF1 Half-duplex Setup Parameters
If you set Word 1, bit 11 to half-duplex (0), the default parameters are
those shown in the table on the following page. If these parameters
are changed and the setup is saved (by changing to software Run
mode), 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 Half-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 the DF1 device.
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 one second 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.
Poll Timeout 200 x 5 ms (0...65,535) x 5 ms Determines the time to wait to be polled by the DF1 master
before a transmission request is ignored.
Message Retries 2 0...254 Determines the number of allowable retries on the DF1 link
before failure.
RTS On Delay 0 x 5 ms (0...65,535) x 5 ms Determines the delay between the RTS (Request to Send)
signal and the start of transmission by the module. This
parameter is only required when communicating with the
type of radio modem that requires a delay after exerting the
RTS signal. It only takes effect if hardware handshaking is
enabled. Refer to your modem user manual.
RTS Off Delay 0 x 5 ms (0...65,499) x 5 ms Determines the delay between the end of the message and
the module setting RTS (Request to Send) inactive. This
parameter is only required when communicating with
modems that require a delay between sending the last
character and raising the RTS signal. It only takes effect if
hardware handshaking is enabled. Refer to your modem
user manual.