Publication 1404-UM001D-EN-E - October 2004
4-2 Communications
Native RS-485 Communications
Your Powermonitor 3000 is set up to communicate via its native
RS-485 port when you first power it up, except for units with an
optional RS-232 communication port. The communications
configuration includes the following parameters:
• Protocol: Allen-Bradley DF1 half-duplex slave, Modbus RTU
slave, or auto-sense. Default auto-sense
• Data rate: Range 1200, 2400, 4800, 9600, 19,200 baud. Default
9600
• Delay: Range 0 to 75 mS, 10 mS default
• Data Format: 8 data bits, 1 stop bit, no parity, odd parity or
even parity. Default no parity
• Node address: Range 1 to 247, default is the same value as the
unit ID listed on the nameplate
• Inter-character timeout: Range 0 to 6553 msec. Default 0 (= 3.5
character times)
The Delay parameter is the time the Powermonitor 3000 waits before
its response to an external request. Certain communications
equipment requires such a delay for reliable operation.
To change your native port configuration, use the Display Module
under the PROGRAM > NATIVE COMMUNICATIONS menu.
You may connect your Powermonitor 3000 into an RS-485 network
with up to 32 nodes connected with 2-conductor shielded twisted pair
cable with a maximum cable length of 1,219 meters (4,000 ft.). The
maximum data rate supported by the Powermonitor 3000 is 19.2
Kbaud. You must use a device configured as a master to communicate
with this port. Error checking method is CRC (Cyclic Redundancy
Check). All devices on the RS-485 network must be set at the same
data rate.
TIP
The native communications port does not support
Data Highway 485 (DH-485) communications.
Although DH-485 uses the RS-485 physical media, its
protocol is not compatible with the DF1 protocol.
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