Impulse 1105 - Manual (Page 8)

Installation
Sealevel Systems DIN485+I Page 6
Operating System Installation (For Windows Users)
RS-422/RS-485 Four Wire Master/RS-485 Two Wire Auto Mode Installation
If your application is 4-wire Full Duplex RS-422 or 4-Wire RS-485 Master, where control of the transmitter is not
required, or 2-wire RS-485 and you intend to use the Auto Mode to control the transmitter, simply connect the
DIN485+I to an existing RS-232 COM: port. This will utilize the Operating System Serial Driver to control the
COM: port. You will want to install Sealevel’s diagnostic utility, WinSSD, to test and verify proper operation of the
port.
Start by choosing Install Software at the beginning of the CD. Choose Asynchronous COM: Port Software,
SeaCOM. Continue with the installation until the “Setup Type” dialog, as shown below, appears. Choose “WinSSD
Utility” to install just the diagnostic tool. A Start Menu Program Group, “SeaCOM” will be created and WinSSD
can be started from there.
RS-485 Two-Wire and RS-485 Four-Wire Slave Installation
If your application is 2-wire Half-Duplex RS-485 or 4-Wire Full-Duplex RS-485 Slave that requires control of the
transmitter, the DIN485+I provides 3 methods of control.
The first method is ‘Auto Enable’ which uses an onboard microcontroller to sense the baud rate and control the
transmitter enable. This mode assumes a minimum baud rate of 1200bps and a word length of 10 bits. This would be
the preferred method, as it requires no software in order to work. This mode should be used with line termination
since the transmitter is driving the line during transmission.
The second method is ‘RTS Enable’ which uses Sealevel’s Windows based serial drivers to control the UART
modem control signal RTS. RTS is connected to the transmitter enable circuit and thru software control, provides an
efficient method of line-turnaround. This abstracts the application from the low level control and simplifies
application development. This mode should be used with line termination since the transmitter is driving the line
during transmission.