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4 Operation
4.
Refer to the Installation and Operation Manual of the specific Powermeter for
instructions on Analog Expander and communication parameters setup.
4.1 Power Up
Close the power feed breaker; the ‘ON’ LED will light up.
4.2 Communication
When you program your powermeter to output data to external analog outputs, the
powermeter periodically updates the AX-8 analog outputs (each 300-500 ms) via
the pair of wires on the RS-422 communications link used for transmitting data. At
that time, the transmission (output) line of the AX-8 is disconnected from the
external network, while the receive line is directly connected to the powermeter
port so that the instrument is constantly ‘listening’ to the network.
When data is requested from the powermeter by a master computer (or controller),
the powermeter instructs the AX-8 to switch the transmission line to the external
network, and then sends the response. After the response message is sent out, the
transmission line is disconnected from the network and the powermeter continues
updating the AX-8 outputs.
The AX-8 can work with different ASCII and non-ASCII network protocols. If you
use an ASCII communications protocol, set the switch #1 on the DIP switch block
S2 to OFF in order to put the AX-8 into ASCII mode. The ASCII message frame
should be ended with two characters CR/LF (ASCII 13 and 10). If you are using
non-ASCII communications protocol such as Modbus or DNP 3.0, set the switch #1
on the DIP switch block S2 to ON to put the AX-8 into binary (transparent) mode. In
this event, the AX-8 will not decode the message frame and the transmission line is
disconnected in 3.5 character time after the response message is sent out.
Indicator LEDs
The AX-8 is provided with a single Rx LED (network indication) and a pair of Rx-Tx
LEDs (Powermeter indication) which operate as shown in
Figure 4-1
:
