MSENSE
®
DGA 9 7045899/02 EN – 11.2020 Page 117
ART
The hardware found in the MSENSE® DGA 9 supports ART (Automatic Receive Transmit Control).
ART is a special RS485 protocol which simply sends the data and turns off the transmission mode of
the corresponding device immediately after the last character has been transmitted. For this type of
protocol, the RS485 communication bus must be equipped with special terminating resistors.
RS485 PC adapter
In order to be able to connect a PC to the RS485 interface of the MSENSE® DGA 9, an adapter
(interface converter) is normally required. Given the characteristics of the RS485 adapter in use, this
must be configured accordingly in MR MSET DGA.
For RS485 communication with MSENSE® DGA 9, only a 2-wire half-duplex mode is available. This
mode requires transmit and receive control, which is guided by manual control (e.g. via RTS signal) or
by ART (Automatic Receive Transmit Control). The adapter should confirm the data sent (echo).
The two check boxes in the MR MSET DGA dialogue box must match the adapter properties:
• Ignore echo
Must be selected if the adapter sends a response.
• RTS transmit control
Must be selected if the adapter requires manual transmit-receive control via the RTS signal.
Response delay
If an adapter with RTS transmit control is used, everything is configured correctly and the communica-
tion still does not work, this may be due to the transmit-receive control. If the adapter does not release
the transmitter quickly enough when sending the data, the response of the MSENSE® DGA 9 is only
partially detected by the adapter (or not at all). Therefore, a response delay should be entered in
MSENSE® DGA 9 (0 ... 2550 ms), in order to counteract this problem.
RS485 Bus-mode
When using the RS485 interface, multiple MSENSE® DGA devices can be connected to one host.
However, it is only possible to communicate with one device at this time. The following figure shows
the schematic topology.
Remark: Naturally, only one host PC is permitted! The host PC with the TCP / IP connection is only
presented as an alternative way of connecting to an RS485 bus. Various third-party vendors have such
network-to-serial adapters in their product range.
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