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Powercom3
Undercover Modbus Unit
User Manual
Revision 04
Camax UK Limited
Unit 8 Jubilee Court
Copgrove
Harrogate
North Yorkshire
Telephone: 01423 340 000
Website: www.camax.co.uk
E-Mail: sales@camax.co.uk
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Table of Contents
1. Introduction ...................................................................................................................................... 4
2. Configuration ................................................................................................................................... 4
2.1. DIP Switch .................................................................................................................................... 4
2.1.1 Address ........................................................................................................................................ 4
2.1.2 Modbus disable ........................................................................................................................... 5
2.1.3 Meter type ................................................................................................................................... 5
3. Device modes ................................................................................................................................... 5
3.1 Program mode ................................................................................................................................ 5
3.1.1 Command set ............................................................................................................................... 5
3.1.1.1 METER command ................................................................................................................... 6
3.1.1.2 RS232 command ...................................................................................................................... 6
3.1.1.3 RS485 command ...................................................................................................................... 6
3.1.1.4 SERNO command .................................................................................................................... 6
3.1.1.5 VERSION command ................................................................................................................ 6
3.2 Non addressed transparent mode ................................................................................................... 6
3.3 Addressed transparent mode .......................................................................................................... 6
Annexure A: Register Map................................................................................................................... 8
Annexure B: Status indication ........................................................................................................... 13
Annexure C: Pinouts .......................................................................................................................... 15
Annexure D: USB Adapter ................................................................................................................ 16
Annexure E: Python Code Examples ................................................................................................. 17
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1.
Introduction
The Modbus Unit has been specifically designed to work with Elster's A1140 and A1700
energy meters and fits under the terminal cover. The power supply of the unit is taken
directly from a A1140 and from an additional power adapter when used with the A1700.
The unit can be configured in one of three modes; modbus mode, transparent mode with
addressing and transparent mode without addressing.
2.
Configuration
The configuration is done via the on-board DIP switch and terminal commands entered via
the RS232 port.
2.1.
DIP Switch
The 8-way switch is divided into 3 groups as follows:
Address
Modbus disabled
Meter type
2.1.1
Address
The address field is bit mapped and has a range of 1 to 31. Switching a bit position to the
on position will add the binary value to the address, e.g.
Address = 1
Address = 2
Address = 1 + 2 = 3
Address = 4
Calculate the address as follows:
Address = sum of value of bit positions set to on.
Each bit position has a value of 2
((bit position)
– 1), so if position 1 and 3 is on the address will
be:
Address = 20 + 22 = 5
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2.1.2
Modbus disable
Set this position to on to disable the modbus functionality. This will result in the unit to
disable any meter protocol and enter the transparent mode.
Modbus enabled
Modbus disabled
2.1.3
Meter type
This selects the meter type, valid settings are:
A1140
A1700
3.
Device modes
3.1 Program mode
Program mode is entered when all dip switch positions are set to the on position.
The program mode command interpreter will listen on the RS232 port (RJ12) at 9600
baud, no parity and one stop bit.
A USB dongle available from Camax UK may be used to gain access to the RS232 port.
3.1.1 Command set
Typing help at the command line displays the available commands, these are: METER,
RS232 and RS485.
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3.1.1.1 METER command
Sets the outstation and password via parameters:
--addr=<outstation>
--pass=<oldpass,newpass>
e.g.
meter --addr=2
meter --pass=FEDC0003,12345678
3.1.1.2
RS232 command
Sets the parameters for the RS232 port (RJ12) via parameters:
--baud=<baudrate>
--parity=<0=none | 1=odd | 2=even>
--stopbits=<1 | 2>
--read-timeout=<milliseconds>
3.1.1.3
RS485 command
Sets the parameters for the RS485 port (RJ45) via parameters:
--baud=<baudrate>
--parity=<0=none | 1=odd | 2=even>
--stopbits=<1 | 2>
--read-timeout=<milliseconds>
3.1.1.4
SERNO command
Display the serial number
3.1.1.5
VERSION command
Display the firmware version
3.2
Non addressed transparent mode
This mode is entered then the address bits are all set to the off position and the modbus
disable bit is set to on. The meter type field is ignored.
In this mode the unit acts as a true RS232 to RS485 converter and all data on both ports
are forwarded to the other port. This mode is useful to daisy chain meters via RS485
when they are spaced further than the RS232 limit.
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3.3
Addressed transparent mode
This mode is entered then the address bits are set to a non zero address and the modbus
disable bit is set to on. The meter type field is ignored.
In this mode the unit acts as an addressable RS232 to RS485 converter. The unit uses a
frame based protocol in the form of:
<frame-delimiter><destination-addr><source-addr><payload><crc16><frame-delimiter>
This mode will allow non addressable devices/meters to be daisy chained onto a RS485
bus.
The protocol definition is available on request.
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Annexure A: Register Map
Instrumentation
Register Address
Description
Data type
100
Total Active Power
float32
102
Phase A Active Power
float32
104
Phase B Active Power
float32
106
Phase C Active Power
float32
108
Total Reactive Power
float32
110
Phase A Reactive Power
float32
112
Phase B Reactive Power
float32
114
Phase C Reactive Power
float32
116
Total Apparent Power
float32
118
Phase A Apparent Power
float32
120
Phase B Apparent Power
float32
122
Phase C Apparent Power
float32
124
Phase A Current Magnitude
float32
126
Phase B Current Magnitude
float32
128
Phase C Current Magnitude
float32
130
Frequency
float32
132
Phase A Voltage Magnitude
float32
134
Phase B Voltage Magnitude
float32
136
Phase C Voltage Magnitude
float32
138
System Power Factor
float32
140
Phase A Power Factor
float32
142
Phase B Power Factor
float32
144
Phase C Power Factor
float32
146
Phase A Current Angle
float32
148
Phase B Current Angle
float32
150
Phase C Current Angle
float32
152
Phase A Voltage Angle
float32
154
Phase B Voltage Angle
float32
156
Phase C Voltage Angle
float32
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