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Many of the drivers available for use with our KEPServerEX product utilize
either RS-422 or RS-485 as their physical communications layer. Your normal
PC comes equipped
only with RS-232 for serial communications. In order to communicate
with an RS-422/485 device your PC will need a converter. Kepware is happy
to announce that we now offer a number of RS-422/485 converter
options from Sealevel Systems.
Sealevel Systems provides a range of converter options that include Isolated or Non
Isolated, Din Rail mounted or Stand Alone converter.
The data sheets for the models offered are as follows:
All of these models feature automatic flow control which is very important in maintaining reliable
RS-485 communications. Additionally, the unit features LEDs for both Transmit and Receive data.
While it may seem like a small thing, it can be very useful to know, at a glance, that
communications is either occurring properly, "Lots of LED activity", or not, "No LEDS".
These units also function as RS-422 converters with the simple flip of a switch.
As mentioned, one of the primary features of any of the RS-485 converters from Sealevel
Systems is their support of automatic flow control. An RS-485 link is typically a half-duplex
conversation, one side talks then the other responds. This half-duplex conversation in most
cases occurs over a single pair of wires. In order for this to work the device at each end
of an RS-485 link must be able to turn its own transmitter and receiver on and off quickly
allowing both ends of the link to share the same pair of wires.
All of the models handle this flow control automatically. Many converters allow the
transmitter and receiver to be controlled by the RTS line from your serial port. Under
WindowsNT 4.0 this can work for most drivers, but there is a bug in the standard Windows95/98
Comm driver which prevents the RTS line from controlling the RS-485 converter. With that in mind,
we always suggest that you use a converter that supports automatic flow control. Now that Kepware
offers these units, we can support your communications needs beyond your PC.
You can learn more about each unit using the complete documentation found here:
Manuals for Converters: ( Adobe Reader)
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