Relay Outputs; Digital Communications Port - Michell Instruments Optidew User Manual

Optidew Series User's Manual
2.3.3

Relay Outputs

There are two sets of relay outputs available via the output connector:
• Alarm Relay
This relay changes state to indicate that the process variable has exceeded
the alarm set point value. The alarm set point value can be adjusted using the
supplied application software (see Section 3.4) or by sending the appropriate
commands to the instrument over RS232 or RS485 (see Appendix B).
• Status Relay
This relay changes state when the instrument is in DCC, DATA HOLD.
In the event of an optics fault, both relays will change state, and the status LED will
fl ash. This normally means the mirror needs cleaning, followed by resetting the mirror
condition during a DCC cycle. Refer to Section 5 for more details.
Refer to Section 2.3 for wiring details.
2.4

Digital Communications Port

The Optidew Series provides either RS232 or RS485 serial communications via a 9
way D-type connector. This allows for communication with a PC, data logger, or other
hardware device.
The following communication settings are required:
For information on installing and using the supplied application software please refer to
Section 3.4.
For a list of serial commands please refer to Appendix B.
NOTE: Changing between RS232 and RS485 communication requires hardware
modifi cations and can only be carried out at the factory.
NOTE: Instruments with a display will only communicate when the display
shows REMOTE mode. (see Section 3.2).
Michell Instruments
Baud Rate
Data Bits
Stop Bit
Parity
Pin No RS232
2
3
5
9600
8
1
None
RS485
Tx
Rx
GND GND
INSTALLATION
B
A
9