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



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


0~100mV,

level signal

4 IN2+IN2+ Second-way load shunt


0~100mV,

level signal

5 IN3- Third-way load shunt


0~100mV,

level signal

6 IN3+IN3+ Third-way load shunt


0~100mV,

level signal

7 IN4-IN4- Fourth-way load shunt


0~100mV,

level signal

8 IN4+IN4+ Fourth-way load shunt


0~100mV,

level signal



specification

1 CAN_LCAN_L CAN

communication

negative

Standard

CAN level

2 CAN_HCAN_H CAN

communication

positive

Standard

CAN level



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

dcem user manual

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