The LEM Norma DM9x0 Series of multimeters are 21000 count CAT II/CAT III hand multimeters with optional RS232 connectivity. The models differ by precision and feature set.

They were also sold as OEM devices by Siemens.

Models

**Norma DM9x0**
Status	planned
Counts	21000
IEC 61010-1	CAT II 600 V, CAT III 300 V
Connectivity	Proprietary 5-pin cable
Measurements	voltage, current, resistance, capacitance, temperature, diode, continuity
Features	autorange, data hold, bargraph, (backlight)

Model	Siemens OEM	Precision (DC)	Backlight	RMS	TRMS	R 20 MΩ	R 200 MΩ	U AC 1 kΩ/V	I 10A	f	C
Norma DM910	B1024	±(0.5% +2d)				●		●
Norma DM920	B1025	±(0.5% +2d)				●		●	●
Norma DM930	B1026	±(0.3% +3d/+2d)	●	●		●		●	●	●	●
Norma DM940	B1027	±(0.1% +3d/+2d)	●	●	● ?	●	●		●	●	●
Norma DM950	B1028	±(0.06% +3d/+2d)	●	●	●	●	●		●	●	●

The RS232 interface is optional. All models were available with or without RS232 interface, the RS232 interface was also available as an accessory.

Hardware

Multimeter

Interface

The RS232 interface consists of the following components:

Interface board (installed inside of multimeter)
Printer cable 5-pin to DB9
PC adaptor (Null modem plug with slightly unusal pinout)

The RS232 interface is designed to allow a direct connection to a serial printer or data recorder. Therefore an adaptor is required to connect it to a PC.

Comm parameters (PC): DTR on, RTS off, RTS/CTS flow control (!).

If the interface cannot be powered from RS232 (e. g. RS232-USB converter with too low voltage), switching on the multimeter with the FUNC button pressed powers the interface from multimeter.

The printer cable has got a power connector (10-16 V DC, 50 mA) to power the multimeter and the interface externally.