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RDD100 User Guide
4 www.honeywell.com
The Demo program or PC terminal emulator port parameters should be set up as follows:
Baud Rate 9600
Start Bits 1
Data Bits 8
Stop Bits 1
Parity None
Local Echo On
Also, configure the program to attach a line feed to the carriage return. This completes the set up of the PC
terminal emulator.
Next, the transducer must be configured to match the above terminal emulator settings. (Settings listed above
are the factory default settings for the HPA, HPB, PPT, PPTE and PPTR, and are therefore likely to be correct.)
2.3 Set Transducer Baud Rate
When a Honeywell digital transducer, connected to a computer as described above, is first powered up a start-up
message will be sent from the transducer. If the transducer baud rate is not set at 9600, either no message or a
garbled message will be received. In this case, it will be necessary to try other baud rates until a match is found.
Possible baud rates for the HPA, HPB, PPT, PPTR and PPTE are: 1200, 2400, 4800, 9600, 14400, 19200, and
28800. Once a match is found, the transducer can be changed to a baud rate of 9600, which will allow it to
communicate with the RDD100 instrument.
The procedure for changing and then storing a new baud rate for the transducer is shown below. The commands
below all use a broadcast address (99) to allow them to operate correctly even if the transducer address has been
changed from the factory default setting, which is address 01.
With the PC and transducer operating at the baud rate found to return a non-garbled start-up message:
Type *99we<cr> (Carriage Return)
Resp *99WE (Command Echo)
Type *99bp=n9600<cr>
Resp *99BP=N9600 (Command Echo)
This will change the transducer to 9600 baud with no parity. Once this command is executed, the PC will again
lose communication with the transducer, since they will be on different baud rates. Do no power down the
transducer at this point since the change is only temporary. The PC terminal emulator can now be changed to
9600 baud and should be able to communicate with the transducer. This can be checked by typing *99p1<cr>
which should return a single pressure reading.
Continue as follows in order to store the new baud rate and parity into the transducer EEPROM:
Type *99we<cr>
Resp *99WE (Command Echo)
Type *99sp=all<cr> (Store Parameters Command)
Resp *99SP=ALL (Command Echo)
After cycling power to the transducer it should now communicate with the PC, set at 9600 baud.
2.4 Setting Transducer Display Units:
Inquiry for the current display units
Type *99du<cr>
Resp ?01DU=PSI (If transducer factory defaults have not been changed.)
Resp *99DU (Command Echo)
To change the display units:
Type *99we<cr>