Detcon DM-600IS - Manual (Page 37)

DM-600IS
DM-600IS Instruction Manual Rev 1.5.9 Page 33 of 37
Examples:
The transmitter is set for a range of 5 ppm.
The display on the transmitter reads 2.74 ppm.
The transmitter is polled for its reading using a Modbus™ command.
The value returned in the response is decimal 274.
Obtain the correct reading by dividing.
274/100 = 2.74 ppm.
The transmitter is set for a range of 25 ppm.
The display on the transmitter reads 22.9 ppm.
The transmitter is polled for its reading using a Modbus™ command.
The value returned in the response is decimal 2290.
Obtain the correct reading by dividing.
2290/100 = 22.9 ppm.
On ranges above 50 ppm there is no math involved. The readings are stored the same as they are seen on the
transmitters display.
15.0 DISPLAY CONTRAST ADJUST
Detcon MicroSafeTM sensors feature a 16 character backlit liquid crystal display. Like most LCDs, character
contrast can be affected by viewing angle and temperature. Temperature compensation circuitry included in
the MicroSafeTM design will compensate for this characteristic; however temperature extremes may still
cause a shift in the contrast. Display contrast can be adjusted by the user if necessary. However, changing the
contrast requires that the sensor housing be opened, thus declassification of the area is required.
To adjust the display contrast, remove the enclosure cover and use a jeweler’s screwdriver to turn the contrast
adjust screw located beneath the metallic face plate. The adjustment location is marked “CONTRAST”. See
Figure 13 for location.
16.0 TROUBLE SHOOTING
Sensor reads Over-range after Power-up
Probable Cause: Biased sensor requiring additional stabilization time.
1. Verify if this is a Biased sensor (see section 6.0).
2. Wait up to 8 hours for unit to come on-scale if using a low range biased sensor.
3. Verify that there is not large amounts of target gas or interfering gases in background.
Reading Higher than Anticipated
Probable Causes: Target or Interfering gases in background, Incorrect calibration for Zero or Span, Biased
sensor still stabilizing.
1. Verify no target or interfering gases are present.
2. Redo Zero and Span calibrations with validated Zero Gas and Span Gas standards.
3. If recovering after a start-up, give more time to stabilize.
Reading Lower than Anticipated
Probable Causes: Target gas or Interfering gases in background during Zero Calibration, Zero Calibration done
before unit finished stabilizing, Incorrect Span Calibration.
1. Redo Zero and Span calibrations with validated Zero Gas and Span Gas standards.