Elgas miniELCOR, Operation Manual, Page: 36 / 131

miniELCOR
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6 Communication with device
For communication with other devices, the device is equipped with one
communication channel which brings it to a total of three communication interfaces.
Either the communication interface RS-232 or the RS-485 can be used for
connection with a superior system. The optical interface is designed for operative
readout or device settings.
In the current firmware version, the device is equipped with several
communication protocols. The device is prepared for extension by other protocols as
required by the customer. The standardly implemented protocols are ELGAS ver.2
and MODBUS
RTU. Preset communication protocol is the same for all
communication interfaces. It is possible to change communication speed for metalic
interface and for optical interface independently.
The ELGAS ver.2 protocol is the native protocol of the device. A complete set of
functions realized in the device is available. The service SW [22] solely uses this
protocol – in case it is necessary to switch to other link level, the ELGAS ver.2
protocol is only wrapped in one other link level (a so called “a tunnel”). The ELGAS
ver.2 protocol is used as the only one for loading firmware (protected by the
metrology mark).
The communication circuits are galvanic separated from other device circuits.
Because of the galvanic separation, the communication circuits must be powered
from outside, from a connected device (CTS signal in case of the RS-232 interface
and U1+ in case of the RS-485 interface).
6.1 RS-232 and RS-485 interfaces
Both interfaces are brought out to the internal terminal board and, although they
are simultaneously functioning, only one of these interfaces can be used (connected)
for communication at a time. Because both of the interfaces are intrinsically safe, it is
necessary during installation to separate the device in a potentially explosive
environment from the connected common device (computer, modem, etc.) by a
consecutive device (DATCOM-Sx, DATCOM-Kx, MTL 5051 etc.), or use a device
with a intrinsically safe design.
The communication speed of the interface (the speed is joint for both interfaces)
and the communication protocol can be set in the device parameters.
Communication via modem controlled by AT commands
Basic setting features of a modem for the correct cooperation with the device:
•
Sending answer (ATQ0)
•
Long format of the sent answers (ATV1)
•
Echo disabled (ATE0)
•
Automatic pickup (ATS0=1)
•
Set firmly serial port communication speed of the modem (e.g. for speed
38400 Bd is command AT+IPR=38400)
•
Ensure presence of power feeding on clamp DSR of the modem (by
command AT&S0). Clamp DSR is interconnected with CTS clamp of
device.
More detailed information must be found in the manual of the used modem.