Download - DCEM User Manual
Emerson Network Power Co., Ltd.
SM-DCEM User Manual
Features introduction
A billing meter for the load of DC power system.
The unit can provide two communication modes:
CAN and RS 485 and can be used for -48V and
+24V system.
Installation
Mounting screws is mainly adopted on the
mounting surface. The mounting method is as
follows: fix the SM-DCEM on the corresponding
mounting place by using four screws respectively to
pass through the mounting hole.
Electrical connection
The SM-DCEM has four sockets: power socket,
sampling input socket for 4-way load shunt, RS485
socket and CAN communication socket for external
electric connection.
J4 J2 J5 J3
The definition of interface is as follows:
� Description of terminal J4:
No. Signal Signal description Signal
specification
1
VBUS+VBUS+
Power supply input
port and bus voltage
detection, positive
pole
0~60V,
power
supply
2
VBUS-VBUS-
Power supply input
port and bus voltage
detection, negative
pole
Reference
grounding
� Description of terminal J2:
No. Signal Signal description Signal
specification
1 IN1-IN1- First-way load shunt
voltage, low potential
0~100mV,
level signal
2 IN1+IN1+ First-way load shunt
voltage, high potential
0~100mV,
level signal
3 IN2-IN2- Second-way load shunt
voltage, low potential
0~100mV,
level signal
4 IN2+IN2+ Second-way load shunt
voltage, high potential
0~100mV,
level signal
5 IN3- Third-way load shunt
voltage, low potential
0~100mV,
level signal
6 IN3+IN3+ Third-way load shunt
voltage, high potential
0~100mV,
level signal
7 IN4-IN4- Fourth-way load shunt
voltage, low potential
0~100mV,
level signal
8 IN4+IN4+ Fourth-way load shunt
voltage, high potential
0~100mV,
level signal
� Description of terminal J5:
No. Signal Signal description Signal
specification
1 CAN_LCAN_L CAN
communication
negative
Standard
CAN level
2 CAN_HCAN_H CAN
communication
positive
Standard
CAN level
� Description of terminal J3:
No. Signal Signal description Signal
specification
1
RS485ARS485A
RS485
communication
positive
Standard
RS485 level
2
GNDGND
Communication
reference
grounding
Reference
grounding
3
RS485BRS485B
RS485
communication
negative
Standard
RS485 level
The wiring diagram of the SM-DCEM is as follows:
�
�
�
�
SM-DCEM
Power system
Emerson Network Power Co., Ltd.
Wiring description:
Connect the two ends of sampling wiring terminal
of each shunt to the voltage sampling input terminal
of the DCEM shunt. Connect power supply wiring
and relative low potential to power supply V-
terminal, connect high potential to V+ terminal.
Note
One end of the shunt of power system shall be directly connected to the negative bus of the system output voltage to avoid the influence of the common mode voltage in event of contactor disconnection and fuse burnout.
Note
The negative end of each shunt shall be directly connected to sampling terminal to ensure measurement precision. It is not recommended to connect the negative end of the shunt to the sampling terminal after the serial connection of the negative end of the shunt.
Use
1. The Run LED (green): if the CAN communication
is normal, Run LED does not flash. If the CAN
communication is abnormal, Run LED flashes once
every second. When the high level monitoring
selects the unit in the menu, it flashes once every 3
seconds. It flashes once every 1/4 second once RS
485 data appears.
2. DIP switch has 4 bits. Different switch
combinations correspond to different alarm
deviation threshold set-points (hereafter referred to
as alarm threshold set-point). The relationship
between Switch state and alarm threshold set-point
is as follows: the operation introduction to mini DIP
switch for SM-DCEM is shown as the following
figure:
The first bit of the DIP switch is used for setting
S485 communication Baud rate. When the switch is
on, the Baud rate is 9600 n 8 1. When the switch is
off, the Baud rate is 19200 n 8 1. CAN’s Baud rate
is consistent, 125K.
The combination of bits 2, 3, 4 of toggle can be
used as the address setting of the equipment.
When the status is on, the value of address is zero.
When the status is off, the value is 1.A1 is low bit
and A3 is high bit. Their corresponding actual
address is different in RS485 and CAN protocol.
CAN address is equal to the value of dialing A
[3..1] , while RS485 address is equal to the value of
dialing A[3..1]+1.
For instance:
The communication address of RS485 equipment
is A[3..1]+1 = 2 to explain that RS485 uses 9600
Baud rates. The address of CAN communication
equipment is 1.
Performance index
Environmental requirement
Operating temperature: -10℃~50℃
Operating humidity : ≤95%
Atmospheric pressure:86kPa~106kPa
Power input and voltage sampling
Rated voltage: DC 48V
Voltage range: DC 20V~60V
Operating current: ≤25mA
Shunt voltage sampling
The maximum sampling is shunt voltage for 4
groups, the voltage range of sampling point is 0~100mVdc.
Noise
Noise at the distance of 1.5m < 50dB
Mechanical parameters
Dimensions: 20mm (Height) x 100mm (Width) x105
mm (Length)
Weight: < 0.5kg