Elgas DATCOM, Operating Instructions Manual

Page: 153 / 228

9
Connecting Inputs
151
The corrector is connected with the encoder by a shielded two-wire cable. The electrical
connection of the encoders with the device is described in Section 5.6.2.5. When making the
connection, the signal polarity must be respected.
The encoder data is transmitted to the corrector in the measurement frequency. Setting a short
measurement frequency shortens the battery life. Section 7.5.1 shows the battery life when using
encoders.
The period of reading the data from the gas meter encoder connected to the instrument by means
of an add-on module located in the SLOT 0 position is limited according to the type of encoder
and the type of module used:
encoder type module (SLOT 0) reading period
SCR+ S0-SCR 10 s ÷ 1 hour
NAMUR
S0-NAM 1 min ÷ 1 hour
S0-EXT1, S0-EXT1/HF 10 s ÷ 1 hour
Table 27 Encoders – limitation of reading period
9.4.1 Device Specifics when using the Encoders
When the encoder is connected, the data communication with the corrector takes place on a two-
wire cable. In addition to transferring the absolute value of the gas meter counter reading,
additional information from the meter can be transmitted (serial number, gas meter constant,
number of nines to reverse the counters, etc.). This additional information is downloaded by the
control firmware of the corrector and used to parameterize the device.
If there is a communication error between the corrector and the encoder, then:
 The "*" flag (asterisk) shows on the display of the corrector at the actual primary volume
value.

If the communication error lasts for more than 10 minutes, the volume difference is added to
the counter after the communication has been restored.
The manual setting of the primary volume V
m
value is blocked for inputs connected to an encoder.
9.4.2 Gas Meter Installing and Replacing
When the gas meter is connected to the corrector, the current reading of the meter is transferred
to the corrector, i.e. the state Vm may change abruptly. In order that this abrupt change is not
falsely reflected in the converted volume Vb (Vbs), the following procedure should be followed:
 In the utility SW [42], [43] running on the PC, display the device parameters, select the "SCR
Encoder" object and press the "Encoder Replacement" button. During the exchange of the
encoder, the processing of volume from the meter will be stopped. (You also need to follow
the instructions displayed on the PC screen).
 Connect the encoder physically to the corrector.
 After connecting the encoder, complete the installation/replacement with the OK button.
During the installation/replacement (i.e. from point 1), no increments are added to the related
counters, and the corresponding counter is marked with an exclamation mark on the display. If
point 3 of this procedure is not performed within one hour of the start of the replacement, the
replacement mode will automatically be terminated in the utility program.