AMC-DTM-Sensor Transmitter
- 17 -
5.3.6 Power Up Sequence
During power up and initialization, the transmitter displays the message “warm-up”, suppresses
gas alarms and leaves fail alarm conditions unaffected. The transmitter output current is also set
to the minimum value. For minimum value, see Table 4-3, 4-20mA Output Specifications.
If the transmitter has an error recorded in its Flash Memory device, the error condition
information is restored from Flash Memory. The following will occur, depending upon the nature
of the error condition:
•
a fail alarm condition and the error code will be displayed for 10 seconds prior to
continuing with the normal power up and initialization, or
•
a fail alarm condition and the error code will be displayed; and, the transmitter will wait
for the operator to press “yes” key to proceed.
A fail alarm condition is de-asserted if no fail condition was detected. Gas Alarms remain
suppressed for further 30 seconds to enable the sensor to stabilize. At the outset of this period,
unit resumes normal operation and raises or clears any alarms as needed.
5.3.7 Manufacturing
Data
The manufacturing data that the transmitter stores is the software version information. This
information is programmed into the non-volatile memory together with the software load itself.
5.3.8
Modbus
The transmitter is a Modbus slave device that supports the following Modbus configuration
options:
•
Modbus device address (1-247).
•
type (RTU or ASCII)
•
RS485 bps rate
The supported Modbus functions and the accessible data are listed in Appendix A, Modbus
Accessible Data.
5.3.9 Test
A Test Mode is provided. When entered, all four relay outputs are activated until any key is
pressed. During testing the 4-20mA current loop is driven to 20mA, all four alarm Light Emitting
Diodes (LEDs) are illuminated and all four alarm relays are asserted.
Note: the keypad timeout
is suppressed during testing.
5.4 Gas Alarm Options
Each of the three alarms has its individual set of Alarm Options.
5.4.1 Threshold
This option is the gas concentration at which the alarm is activated subject to Activation Delay.
