Appendix A: Communications
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Appendix A: Communications
This section describes the Modbus communications protocol employed
by a meter with the Megawatt option in a Modbus network. It is assumed
that the user is familiar with serial communications in general, and the
Modbus protocol. Refer to the document 9200 Modbus Protocol for more
information.
Modbus Address Table
In the following Modbus map, many numeric measurements are scaled.
Scaling is either fixed or programmable.
For an example of fixed scaling, suppose that the frequency register 40115
contains the value 5987. Since this register is scaled by "x100" the actual
measured value is 59.87 Hz.
For an example of programmable scaling, suppose that the meter Vln a
value is 480.1. If the PVS scaling is set to "x10" (default), then register 40100
will contain a value of 4801. If the PVS scaling is set to "0.1," then register
40100 will contain a value of 48. The meter supports programmable
scaling for voltage (PVS), current (PCS), neutral current (PnS), and power
(PPS).
Modbus Addr Meter Measurement Format Scale Default Scale Description
40001 manufacturer's ID UINT32 x1 See note 1.
40003 firmware revision UINT16 x1
40004 oem ID UINT16 x1 See note 2.
40005 meter options UINT32 x1 See note 3.
40007 # meter power ups UINT16 x1
40008
# peak demand
resets
UINT16 x1
40009 meter on-time UINT32 x1 See note 4.
40011 # flash erase cycles UINT32 x1
40013 device type UINT16 x1 See note 5.
40014 Reserved
40015
demand interval
down counter
UINT16 x1
Reserved
40100 kVln a UINT16 PVS x10 See note 6.
40101 kVln b UINT16 PVS x10
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