Sensaphone SCADA 3000 Users manual - Manual (Page 113)

12-1
Chapter 12: Radio Programming
Chapter 12: PROGRAmmING FOR
RADIO
APPLICATIONS
INTRODUCTION
Wireless communication with one or more SCADA 3000s may be accomplished via radio
modems. In this scenario, one radio modem would be connected to the host computer and
additional radio modems would be connected to each SCADA 3000 on the network.
• The transmit frequency of the host PC radio modem must match the receive fre-
quency of the radio modem at each SCADA 3000. Similarly, the receive frequen-
cy of the host PC radio modem must match the transmit frequency of the radio
modem at each SCADA 3000.
• The host computer can be used to program an individual unit or to poll each unit
on the network to update a real-time screen.
• Each unit on the network must have a unique modbus ID. The host computer
will request information from a unit based on its modbus ID. As a result, all of
the SCADA 3000 units will “hear” the request for information, but only the unit
with a matching modbus ID will actually respond.
SeLeCTING RADIO mODemS
There are numerous manufacturers of radio modems, but they all differ slightly. A listing is
provided at the end of this section. Some of the options that must be considered when selecting
a radio modem include:
licensed/unlicensed operation
baud rate requirements
cost
power requirements
geographical constraints
While most of these issues will depend upon your particular circumstances, we can give you
some general information to start off with. Licensed frequency radios are generally cheaper but
they require registration with the FCC. Unlicensed radio modems (spread spectrum), while
usually more expensive, can be faster to get up and running. Both types of radio modems may
be used with the SCADA 3000. The baud rate of the radio modem will determine how quickly
information will be transmitted and received. The SCADA 3000’s COM2 port can operate
over a range of 1200bps to 38.4Kbps. Faster radio modems generally cost more. Consider a
radio modem that can communicate at 38.4Kbps for networks with many SCADA 3000 units.
Power requirements will vary for different radio modems. Most operate from a 12V supply.
Radio modems with greater distance capability typically require more power. Be sure that your
power source is capable of powering the radio modem. Geography may determine whether a
radio modem can be used at all. Typically, mountainous regions will not work. Line of sight
provides the best chances of error-free data transmission.
CONFIGURING SCADA 3000 FOR USe WITH RADIO mODemS
The SCADA 3000 COM2 port is configured for connection Directly to a radio modem. A
null modem adapter is not required. Set the serial port baud rate and flow control jumper as
described in Appendix D. These must be set to match your radio modem. The COM2 serial
port may be configured with flow control enabled or disabled. Flow control is enabled when
the COM port configuration jumper is set to the Radio position. In our experience most radio