Vaisala HMT360 - Manual (Page 52)

User’s Guide ______________________________________________________________________
50 ___________________________________________________________________ M010056EN-J
Serial Interface
Use the serial interface for calibration and testing purposes in safe areas
only. Always use the serial interface cable (optional accessory, Vaisala
order code: 25905ZZ). Connect one end of the cable to the serial port of
your computer and the other to the connector marked "RS232C" on the
electronics unit of the transmitter (see
Figure 7 on page 24 ).
Serial Communication Settings
WARNING The serial interface MUST NOT be used in hazardous areas.
NOTE With serial communication the current consumption increases
approximately to 7 mA and the transmitter is not able to operate with
4 mA. Therefore, it is recommended to use serial communication only
temporarily for changing settings or for calibrating the transmitter in a
safe area. With serial port, the minimum supply voltage is 15 VDC.
NOTE The transmitter incorporates a serial interface detector. However, not all
terminals or PC serial ports (for example, optoisolated or ports not
meeting RS232C standards) recognize this standard. If the
communication is not possible via a serial interface, use a forced
activation by pressing simultaneously buttons Up and E on the
transmitter cover. To deactivate the forced activation, press these buttons
again or reset the transmitter. If the transmitter does not receive any
commands for half an hour, it automatically closes the serial
communication.
Table 5 Serial Communications Settings
Parameter Value
bauds 2400
parity none
data bits 8
stop bits 1
CAUTION When using the serial interface, be sure that power supply and serial
interface are not connected to the same ground (use a floating power
supply or hand-held serial interface device).