Lovato DMG800 and DMG900

Compatibility

Compatible with EpiSensor Edge over Modbus RTU or Modbus TCP

The DMG800, DMG900 and DMG900T are compatible with EpiSensor Edge over Modbus RTU on an EXP1012 RS-485 module (or the DMG900T's built-in RS-485 port), read through a ZMB-31 Modbus Interface or a Gateway serial port, and over Modbus TCP on an EXP1013 Ethernet module. Lovato publishes the register table with addresses, formats, units and model columns for read functions 03 and 04.

DMG800, DMG900 and DMG900T, read with the DMG800 and DMG900 columns of protocol document I317IGB02_22 and manuals I272IGBFE02_17 and I273IGB02_17. A DMG800 or DMG900 needs an EXP1012 or EXP1013 module before it can be read; EXP1011 (RS-232), EXP1010 (USB) and EXP1014 (Profibus DP) are outside this guide. Site check: read frequency at table address 0032H and compare it with the display. Read-only monitoring: no writes to setup or command registers.

Connect it with

• Modbus Interface ZMB-3X From €399 ex VAT Configure
• Gateway ZGW-20 From €899 ex VAT Configure
• Evaluation Gateway on a Raspberry Pi Edge with one device licensed Free Set up

Models

Specifications

The DMG800 and DMG900 suit a switchboard door where a local display and more than 300 (DMG800) or 500 (DMG900) readings are wanted. Both are three-phase meters for single-, two- and three-phase systems with or without neutral, read through external CTs, and both are expanded at the rear with EXP modules for communication, I/O, analog signals and data memory.^2, 3

Order codes

DMG800 (EAN 8013975180549) and DMG900 (EAN 8013975180563); DMG900T transducer; D048 versions for a 12 to 48 VDC supply.^3, 6, 7

Communication

No built-in port on the DMG800 or DMG900. Up to two communication modules (COM1 and COM2): EXP1012 isolated RS-485 or EXP1013 isolated 10/100 Mbit/s Ethernet with TCP/IP. The DMG900T has a built-in RS-485 port.^{2, 3, 4, 5}

Modbus settings (M07)

Node address 01 to 255 (default 01); 1200 to 115200 bit/s (default 9600); 8 bits with no, odd or even parity, or 7 bits for ASCII; one or two stop bits; Modbus RTU (default), ASCII or TCP; IP port 0 to 9999 (default 1001).^2, 3

Voltage inputs

690 V L-L (400 V L-N) maximum rated; measuring range 20 to 830 V L-L and 10 to 480 V L-N. The DMG900 adds a neutral-to-earth channel, 1 to 480 V.^2, 3

Current inputs

External CTs with 1 A or 5 A secondary. On the 5 A scale the DMG800 measures 0.010 to 6 A and the DMG900 0.010 to 10 A. The DMG900 has a fourth CT input for the neutral.^2, 3

Accuracy

Voltage ±0.2% and current ±0.2% ±0.5 digit within the stated ranges; active energy class 0.5S (IEC/EN 62053-22), reactive energy class 2 (IEC/EN 62053-23).^2, 3

Auxiliary supply

100 to 440 VAC or 110 to 250 VDC, 3.9 VA or 3.4 W maximum; D048 versions 12 to 48 VDC.^2, 3

Housing

96 x 96 mm flush mount to IEC 61554, IP65 at the front and IP20 at the housing and terminals. The DMG900T mounts on a 35 mm DIN rail and is IP20.^2, 3

Environment

Operating -20 to +60 °C, storage -30 to +80 °C, relative humidity below 80%.^2, 3

Certifications

cULus, EAC and RCM.^2, 3

Interface

Documented measurements and integration boundaries for DMG800 and DMG900.

• Addresses are the table addresses printed by Lovato in hex. Send each one minus one, as Lovato's own example does (L2 active power at 0016H is requested as 00 15), with function 03 or 04 and at most 80 registers per request.
• Two-register values are 32-bit with the high word first: Lovato's example reply 00 01 FB 00 for L2 active power is 129792, or 1297.92 W at W/100.
• Phase voltages L1, L2 and L3 at 0002H, 0004H and 0006H and line voltages L1-L2, L2-L3 and L3-L1 at 000EH, 0010H and 0012H: unsigned 32-bit, V/100.
• Phase currents at 0008H, 000AH and 000CH and neutral current at 0048H: unsigned 32-bit, A/10000. On the DMG900 the measured neutral current from the fourth CT is at 006CH and the neutral-earth voltage at 006AH (V/100).
• Phase active power at 0014H, 0016H and 0018H and total (equivalent) active power at 003AH: signed 32-bit, W/100. Phase reactive power from 001AH and total at 003CH in var/100 (signed); phase apparent power from 0020H and total at 003EH in VA/100 (unsigned).
• Power scale: when the CT and VT ratios allow more than 5 MW per phase, every power reading switches to 1/10 W. Address 2F70H returns 0000h while the normal 1/100 W scale is in use; it is listed from software revision 09 on the DMG800 and 06 on the DMG900.
• Phase power factor at 0026H, 0028H and 002AH and total power factor at 0040H: signed 32-bit, divide by 10000. The DMG900 also gives cos phi per phase at 002CH, 002EH and 0030H.
• Frequency at 0032H: unsigned 32-bit, Hz/1000. Voltage and current unbalance at 0042H to 0046H and THD of voltage at 0054H to 0058H and current at 005AH to 005EH, in %/100.
• Energy Edge reads: total imported active energy at 1A20H, exported at 1A22H, imported reactive at 1A24H, exported reactive at 1A26H and apparent at 1A28H, with partial counters from 1A2AH to 1A32H. Two registers each, unsigned 32-bit, kWh/100 (kvarh/100 or kVAh/100). Lovato states that they roll over to 0 after 19 999 999.99 kWh.
• The four-register energy counters at 1B20H to 1B44H and the tariff counters from 1B48H (four tariffs on the DMG800, eight on the DMG900) are unsigned 64-bit values, which Edge's Modbus client does not read. Use the 1A20H counters.
• Maximum, minimum, average and maximum demand copies of the instantaneous readings start at 0400H, 0600H, 0800H and 0A00H. Total hour meter at 1E00H and partial hour meter at 1E02H: unsigned 32-bit, seconds.
• Commands at 2FF0H and 2F01H (function 06) reset energy, peaks and alarms or reboot the meter, and setup parameters sit above 1000H. Keep every write out of a monitoring poll.

Setup

1. Identify the meter and its modules

   Open the expansion modules page on the display and note which EXP modules are fitted and which COM channel each one is. A DMG800 or DMG900 with no EXP1012 or EXP1013 cannot be read by Edge. If your tool supports function 17 (Report slave ID), type B4h is a DMG800 and BEh a DMG900; record the software revision byte that follows.

2. Check CT, VT and wiring settings

   Compare menu M01 with the installation: CT primary and secondary (1 or 5 A), VT use and ratio, and the wiring type in P01.07. Run the wiring test (command C.16) on a loaded circuit to catch phase sequence and CT polarity errors before readings are collected.

3. Set the communication channel

   In menu M07, open the COMn section for the module you will use. For RS-485 leave the protocol on Modbus RTU and copy the node address, speed, data format and stop bits into Edge or the ZMB-31. For Ethernet choose Modbus TCP, set the IP address, subnet mask and gateway, keep the server role and note the IP port (1001 from the factory).

4. Wire the RS-485 line

   Connect A, B and SG on the EXP1012 (or the DMG900T RS485 terminals) as a single daisy chain of shielded twisted pair, and follow Lovato's RS-485 connection diagram for the TR terminal. Plan any line longer than 1200 m, or with more than 31 meters, with repeaters as that diagram shows.

5. Start with the frequency read

   Read frequency with the example below and compare it with the display. Then add voltages, currents, power and the 1A20H energy counters, checking each new point against the matching display page.

Common questions

Does a DMG800 have a Modbus port?

Not on its own. The DMG800 and DMG900 talk Modbus only through EXP communication modules plugged into the rear: an EXP1012 for isolated RS-485 or an EXP1013 for Ethernet, with at most two communication modules per meter. The DMG900T transducer is the exception, with a built-in RS-485 port chosen by DIP switches.^1, 2, 3

Why send 0x0031 when the table says 0032H?

Lovato's protocol document says the address in the query must be one less than the address in the table, and its own example reads L2 active power, listed at 0016H, with address bytes 00 15. A client that asks for one-based register numbers takes the table value; one that sends the raw address takes the table value minus one.¹

Which energy registers should Edge read?

Use the two-register counters from 1A20H: unsigned 32-bit values in kWh/100 that roll over after 19 999 999.99 kWh. The four-register counters from 1B20H are 64-bit, which Edge's Modbus client does not read.¹

Why does Modbus TCP not answer on port 502?

The DMG800 and DMG900 manuals give 1001 as the factory value of the IP port parameter P07.n.08, with a range of 0 to 9999. Point the Edge Modbus TCP client at port 1001, or change P07.n.08 to 502 if the site standard needs it.^2, 3

Are the DMG800 and DMG900 still sold?

Lovato's online catalogue shows both product pages marked Out of Catalogue, while their manuals, the EXP modules and the DMG protocol document remain available for download. Plan replacements with Lovato before an estate depends on new DMG800 or DMG900 units.^6, 7