Eaton Power Xpert PXM 4000, Руководство пользователя и инструкция по установке

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G.3. PXMCM Com 0 and Com 1 RS485 bias resistors (Terminals CM3,
Each RS485 link requires a set of fail safe bias resistors to guarantee that the line goes to
a marked state while the line is idle.
The meter convention is to set the 750 ohm bias resistors at the Master node only.
• The RS485 Com ports on the PXMCM card default to Slave functions, therefore the
factory default jumper postion is N for no bias.
• Com 0 jumpers are set to N for use on the display’s network.
• Com 1 can be programmed to be a Master Gateway. This requires changing the posi-
tons of jumpers C1A and C1B from N to Rb.
• To change the jumper position, the PXMCM board must be removed from the meter.
See general card removal guidelines.
• There are two bias resistors per port to bias each data line. Both jumpers should be set
to the same position (N or Rb).
• The jumpers designators are stenciled as C0 A and C0 B; C1A and C1B. Positions N
are for not engaged and positions Rb are for engaged. See illustration on the following
page.
• Com 0 has jumpers C0 A and C0 B
• Com 1 has jumpers C1A and C1B
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