ICP DAS USA GW-7838-M User manual

User Manual
Version 1.0.1 Oct 2021
GW-7838-M
(Modbus TCP Server to M-Bus Master Gateway)

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：2
Copyright © 2020 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
Table of Contents
1. Introduction .........................................................................................................................4
1.1 Features..........................................................................................................................5
1.2 Specification....................................................................................................................6
2. Getting Started ....................................................................................................................7
2.1 LED Indicator..................................................................................................................8
2.2 DIP Switch ......................................................................................................................9
3. Configuration and Communicate test .............................................................................10
3.1 Connect.........................................................................................................................11
3.2 Baud Rate and Data Format Settings ...........................................................................12
3.3 M-Bus Meter Settings....................................................................................................13
3.3.1 Import.....................................................................................................................14
3.3.2 Export.....................................................................................................................16
3.3.3 Add.........................................................................................................................17
3.3.4 Save.......................................................................................................................19
3.3.5 Delete.....................................................................................................................21
3.3.6 Delete All ................................................................................................................23
3.4 M-Bus Meter Communicate Test...................................................................................24
4. Meter Configuration Label Description...........................................................................25
4.1 Serial.............................................................................................................................26
4.2 Protocol.........................................................................................................................27
4.3 SubCode.......................................................................................................................28
4.4 Medium.........................................................................................................................29
4.5 Value.............................................................................................................................30
4.6 Unit ...............................................................................................................................31
4.7 Cycle.............................................................................................................................32
4.8 Description....................................................................................................................33
4.9 Register.........................................................................................................................34
Appendix A. Firmware Update ................................................................................................35
Appendix B. Revision History.................................................................................................36

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：3
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
Important Information
Warranty
All products manufactured by ICP DAS are under warranty regarding
defective materials for a period of one year, beginning from the date of
delivery to the original purchaser.
Warning
ICP DAS assumes no liability for any damage resulting from the use of this
product.ICP DAS reserves the right to change this manual at any time
without notice. The information furnished by ICP DAS is believed to be
accurate and reliable. However, no responsibility is assumed by ICP DAS
for its use, not for any infringements of patents or other rights of third parties
resulting from its use.
Copyright
Copyright @ 2020 by ICP DAS Co., Ltd. All rights are reserved.
Trademark
Names are used for identification purpose only and may be registered
trademarks of their respective companies.
Contact us
If you encounter any problems while operating this device, feel free to contact us
via mail at: [e-mail] . We will reply as soon as possible.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：4
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
1. Introduction
The M-Bus ("Meter-Bus") is a standard for remote reading of meters. It is usable for most
types of consumption meters as well as for various sensors and actuators. The GW-7838-M
is specially designed for M-Bus slave device. It offers Modbus TCP communication by
Ethernet and Modbus RTU communication by RS-232. On hardware the GW-7838-M has a
6-bit dip switch for serial port and M-Bus port baud rate. GW-7838-M supports Modbus
TCP/RTU function code 0x03 and 0x04 to read data of M-Bus meters. Through this design, it
is easy to communicate with any standard M-Bus slave.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：5
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
1.1 Features
Supports M-Bus standard: EN-13757, CJ/T -188
Supports Modbus TCP/RTU function code 0x03 and 0x04 to read Meter data
Baud rate: Adjustable by dip switch for M-Bus and serial port from 300 to
115200 bps.
Default M-Bus port data format: Data bit 8, Parity Even, Stop bit 1
Supports up to 100 M-Bus slaves
M-Bus over current protection
Short-circuit protection on the M-Bus
Update firmware from serial port
Provides PWR, MTX and MRX 3 LED indicators
Watchdog inside

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：6
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
1.2 Specification
Module GW-7838-M
M-Bus Interface
Channel 1
Baud Rate (bps) 300 bps ~ 2400 bps
Data bit 5, 6, 7, 8
Stop bit 1, 2
Parity None, Even, Odd, Space, Mark
Isolation 3750 Vrms for photo-couple
ESD Protection Contact ±4 kv class B
Current Protection short-circuit protection
UART Interface
Channel 1 RS-232
Baud Rate (bps) 300 bps ~ 115200 bps
ESD Protection Contact ±4 kv class B
Ethernet Interface
Channel 1
Protocol Modbus TCP
Power
Power Supply Unregulated +10 ~ +30 VDC
Protection Power reverse polarity protection, Over-voltage brown-out protection
Power Consumption
1.8 W @ 24 VDC (with 1 slave device)
11.8 W @ 24 VDC (with 100 slave devices)
Mechanical
Installation DIN-Rail
Dimension (W x L x H) 72mm x 122mm x 33mm
Environment
Operating Temperature -25 to +60°C
Storage Temperature -40 to +80°C
Relative Humidity 10 to 90% RH, Non-condensing

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：7
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
2. Getting Started
Appearance and pin assignments

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：8
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
2.1 LED Indicator
The GW-7838-M module provides three LED indicators, including indicators for power status and
module status. The Following is an overview of the purpose and function of each LED indicator
together with a description.
LED Name
LED
Status
LED Description
Power (Yellow) ON The power of the module is ON
Power (Yellow) Flashing
M-Bus overload (short or too much M-Bus slaves)
Need reboot to recover the status.
MTX (Green) Flashing M-Bus communication normal Tx
MRX (Green) Flashing M-Bus communication normal Rx
*

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：9
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
2.2 DIP Switch
The GW-7838-M module provides 6-bit dip switches and the first two bits are used to change
operation mode. The following is an overview of the purpose and function of each dip switch
position together with a description. After changing the configuration of the DIP switch, the
GW-7838-M needs to reboot to enable the new setting.
1 (Init)
2 (Mode)
Description
OFF
OFF
Normal Work
ON
OFF
Firmware Update
OFF
ON
Configuration mode
ON
ON
Reserve
The DIP switch 3 ~ 6 are used to set RS-232 and M-Bus baud rate. The following is an overview
of the purpose and function of each dip switch position together with a description. After
changing the configuration of the DIP switch, the GW-7838-M needs to reboot to enable the new
setting.
3
4
5
6
M-Bus baud rate (bps)
OFF OFF OFF OFF 300
ON OFF OFF OFF 600
OFF ON OFF OFF 1200
ON ON OFF OFF 2400
OFF OFF ON OFF 4800
ON OFF ON OFF 9600
OFF ON ON OFF 19200
ON ON ON OFF 38400
OFF OFF OFF ON 57600
ON OFF OFF ON 115200
Others
User-defined
Note: M-Bus only supports baud rate from 300 to 2400 bps.
Default M-Bus data format is 8, e, 1.
Default RS-232 data format is 8, n, 1.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：10
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3. Configuration and Communicate test
The configuration for the module parameters or communication setting on the GW-7838-M
module can be performed via M-Bus utility. The M-Bus utility can be downloaded from the
following website:
https://www.icpdas.com/en/download/index.php?model=GW-7838-M
The figure below is an illustration of module wiring. Connect the PC COM port to the RS-232 port
and connect M-Bus meter to M-Bus port of the GW-7838-M. Set the DIP switch to the
configuration mode and then power it on.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：11
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3.1 Connect
Execute the M-Bus utility. There will be a connection diagram as first.
Click “Configure” tab page, choose the corresponding COM port in PC, or select Ethernet and
input GW-7838-M IP Address then click “Connect” button to connect with module. Please be
noted that the UART baud rate of GW-7838-M will be 115200bps when it is in configuration
Mode.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：12
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3.2 Baud Rate and Data Format Settings
The first page of the utility lists baud rate and data format configuration of the serial port and the
M-Bus port and it also shows the Modbus node ID and IP related parameters of the GW-7838-M.
User could add a new baud rate and data format setting or change IP address as need in this
page. In addition, because of the slow response of some M-Bus meters, the utility also provides
an M-Bus timeout setting “M-Bus Timeout”, which users can adjust according to their needs.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：13
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3.3 M-Bus Meter Settings
In the “Meter” page of the utility, user could configure the M-Bus communication setting by using
“Import” or “Add” functions. The usages of these functions are listed as following sections.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：14
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3.3.1 Import
There are two ways to add M-Bus Meter setting into GW-7838-M. One is using “Import” to
import an existed configuration file and save to GW-7838-M. The configure steps are as
following:
Step1: Press “Import” button.
Step2: Open an existed configuration file of XML format.
Step3: The configuration will be loaded into the utility as following:

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：15
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
Step4: Press “Save” button and confirm to save configuration.
Step5: After saving success diagram showed, set the DIP switch to operation mode and reboot
the module.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：16
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3.3.2 Export
User could export the existed module configuration to a XML file by the “Export” function.
Step1: Press “Export” button. Then select path and input file name to export the configuration.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：17
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3.3.3 Add
The second way to add meter configuration to GW-7838-M is using “Add” function. The “Add”
function can add meter of EN-13757 protocol or CJ/T-188 protocol into GW-7838-M. Refer below
operation example for detail setting step.
Step1: Press “Add” button and select the protocol of the meter. There are two protocols,
EN-13757 and CJ/T188 for select. Input the meter serial number and M-Bus network polling
cycle time. Then press “OK” to connect to the meter.
Some meters supported several data group, this calls subcode. If the data of user needs at
different subcode, user can input the subcode number at “Application reset subcode” field. There
can add several different subcode in one meter. If user needs not the subcode field, please keep
it empty. The below example is using subcode 0x01.
Note: The meter serial number of EN-13757 is 8 numbers, and the serial number of CJ/T188 is
14 numbers.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：18
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
Step2: The meter information shows as below.
Step3: After add all meters on the utility list, press “Save” to save these parameters to the
GW-7838-M.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：19
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
3.3.4 Save
After adding meters setting or importing configuration, use “Save” function to save configuration
into the GW-7838-M.
Step1: Press “Save” button.
Step2: Confirm to save the configuration.

GW-7838-M (Modbus TCP Server to M-Bus Master Gateway) User Manual Version 1.01 Page：20
Copyright © 2021 ICP DAS Co., Ltd. All Rights Reserved E-mail: [e-mail]
Step3: After saving success diagram showed, set the DIP switch to operation mode and reboot
the module.