AccuEnergy AcuRev 1312, Руководство пользователя

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V: 1.0 Revised: Aug. 2017
AcuRev 1312
20
DIN-Rail Power Meter
Communication
The AcuRev 1312 supports Modbus-RTU protocol through it’s built-in RS485 port. The RS485
terminals are denoted as ‘A’, ‘B’ and ‘S’. ‘A’ is the positive diff erential terminal, ‘B’ is the negative
diff erential terminal and ‘S’ is for connecting the shield of the shielded twisted pair cable.
The maximum distance of the cable should not exceed 1200m. This distance should be shorter if
more devices are connected to the same communication link or if using a higher baud rate.
If the master device does not have a RS485 port but a RS232 port then a RS232-RS485 converter
should be utilized.
Please use the following to improve the communication quality:
⚫ Use a high quality shielded twisted pair cable, AWG22 or lower is suggested.
⚫ Pay attention to single point earthing. This means that there is only one side for the shield
to be connected to the ground in a communication link.
⚫ Every A(+) should be connected to A(+), and B(-) to B(-).
⚫ ‘T’ type topologies should be avoided. This means no new branches can be formed except
from the starting point.
⚫ Keep the communication cables away as far as possible from sources of electrical noises.
When several devices are connected in daisy chain to the same long communication line, a
anti-signal refl ecting resistor (typically 120-300Ohms, 0.25W) should be used at the end of
the circuit (the last device of the chain).
⚫ Use a RS232/RS485 or a USB/RS485 converter with optical isolated output and surge pro-
tection.