PQube 3 Instruction Manual
Page 62 of 103
5.5
Modbus Setup
5.5.1
Basics
Your PQube 3 has a built-in Modbus-over-TCP server that you can use to read meters and
determine when new event or trend recordings are available.
You can set the following parameters in your PQube 3’s setup.ini file:
Modbus Base Address:
The global base address from which all registers are offset. Default is
0x7000.
Modbus Query Port:
The TCP/IP port on which the Modbus server listens. Default is port 502.
Modbus Byte Order:
Data values spanning multiple registers (such as floats) can be reported in BIG
ENDIAN or LITTLE ENDIAN. Default is BIG_ENDIAN.
Modbus Slave ID:
The PQube can be assigned a slave ID required in queries. Default value is 0x1.
5.5.2
Scan rates, client load, and limitations
The Modbus protocol limits single query register results to 125 registers per scan. A scan of sets of
registers can occur at client, PQube, and network speeds.
However, the PQube3 modbus register
values only update at the internal meter update rate, which is around 2 Hz.
Therefore, high rate
scans of values in sets of registers will only change returned at 2 Hz, even if scanning at higher rates
is supported.
The PQube supports multi-client, multi-session modbus, with conventional limit to 10 clients at a
time. This value can be changed internally in software.
5.5.3
Supported Clients
The PQube3 supports the
PSL Modbus Client
, third party free Modbus clients, or any software
conforming to the Modbus protocol (such as groov).
5.5.4
Register List (refer to Modbus Reference Manual)
Refer to the
PQube 3 Modbus Reference Manual
for the register tables.
5.5.5
Downloads
The
PSL Modbus Client
and
PQube 3 Modbus Reference Manual
are available for download at:
http://www.powersensorsltd.com/PQube3_Reg.php
Shop for Power Metering products online at:
1.877.766.5412
www.
PowerMeterStore
.ca
