Remote Processing CX-10 User Manual
Page 23
SERIAL PORTS
BASIC
SECTION 4
Page 4-6
RADIO MODEM
Using radio modems in a network is similar to using RS-
485 in a network. The only real difference is the modem
connects to the CX-10 through P5.
The modem is a Maxstream / Digi International XT09-
SI. This part is available directly from the manufacturer
at
www.maxstream.net
(alternate
www.digi.com
) or
from Digikey
www.digikey.com.
The modem is licence free, 900 Mhz spread spectrum
radio. Maximum range is 3000 feet in indoor/urban
environments and up to 20 miles with a high gain
antenna and line-of-site conditions.
This modem can be configured in a number of different
ways. Modems shipped from Remote Processing are
programmed in the following configuration:
Serial interface Baud rate: 19200
RF baud rate: 9600
Transmit power level: 500 mW
Destination address: 7975
Address mask: 7975
Source address: 7975
GP01 configuration: RS485 TX active high
The lower RF baud rate allows for further distances. The
unique addresses prevent other similar devices from
interfering with other similar 900 Mhz modems.
Using the RF modem limits modbus packet sizes. A
maximum of 122 integers and 61 float registers may be
sent/received at any one time.
RF Modem Power ON/OFF control
The RF modem power may be turned on or off through
register 4825. A 1 written turns on the modem. ON is
default. A 0 written to this register turns off the modem.
This is a non-volatile register, meaning its state is stored
in EEPROM and will retain the last programmed state on
power up or reset.
Turning off the modem saves about 90 milli-amperes.
ACCESSING SERIAL BUFFERS
Access COM0 and COM3 buffers in Basic by using the
GET(n) function: This function only works for COM 0
when COM3 is configured for modbus operation.
If COM 3 is in ASCII mode, use GET(3) to retrieve data.
If there is no data in the COM0 or COM 3 port, a value
of 256 is returned.
When COM 3 is in modbus mode, the only way to access
data in the buffer is when COM 3 is running a Basic
program and is in master mode. Master mode is
automatically entered using the PRINT #3 command.
Buffer data (variants) are retrieved using register 4782.
See registers 4781-4783 for more information.
DISABLING CONTROL-C
Program execution is terminated by entering a
execution is not terminated, execute the following
statement:
DBY(38) = DBY(38) .OR. 1
WARNING:
Make sure you have a way of stopping program
execution in your program. There is no way to stop
program execution by external means.
APPLICATION PROGRAMS
The following programs are in the Basic Demo directory.
File
Description
COM 3 ASCII MODE.bas
COM 3 PRINT and
GET(3) commands
master 3 4051ints.bas
Modbus master mode
query demo.
master 16 4051ints.bas
Modbus mster mode,
write demo