Laurel Electronics LTM DPM SERIES ANALOG INPUT, SERIAL DATA OUTPUT - Manual (Page 4)

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3. INTRODUCTION, SERIAL OUTPUT “DPM” SERIES TRANSMITTERS
This manual covers DIN rail transmitters with serial data output and an analog input signal
conditioner. These transmitters duplicate the signal conditioning and signal processing features
of digital panel meter counterparts for exceptional accuracy at high read rate. When the serial data
output is utilized, there is no degradation in accuracy due to a digital-to-analog converter.
A wide range of analog signal sources are accommodated by five signal conditioners:
• DC input for volts, amps, process signals (e.g., 4-20 mA), and strain gauges. Most sensitive
full scale input range of 200 mV. Built-in 5A current shunt.
• AC rms input for volts and amps. Can be AC or DC coupled. Built-in 5A current shunt.
• Load cell or microvolt input with selectable full scale input ranges from 20 mV to 500 mV.
• Thermocouple temperature input for seven thermocouple types.
• RTD temperature or Ohms input for Pt100, Ni120 or Cu10 RTDs, 20Ω to 200 kΩ resistance.
Serial communications are standard. The transmitter serial port is default jumpered for RS232 or
full-duplex RS485 (same jumper settings). Half-duplex RS485 is also selectable either via internal
or external jumpers. Three serial protocols are software selectable: Modbus RTU, Modbus ASCII
and Custom ASCII. Modbus allows devices by different manufacturers to be addressed on the
same data line. The simpler Custom ASCII protocol is recommended when there are no devices by
other manufacturers on the data line.
An isolated 4-20 mA, 0-20 mA or 0-10V output is standard. This output is generated by an ultra-
linear 16-bit digital to analog converter which tracks an internal linearized digital reading.
An isolated transducer excitation output is standard. Three output levels are jumper selectable:
5V at 100 mA, 10V at 120 mA, or 24V at 50 mA. The factory default setting is 10V and can power
up to four 350 ohm load cells in parallel.
Dual solid state relays are standard. These are rated 130 mA at 140 Vac or 180 Vdc.
Isolation to 250V rms is provided for power, signal input, analog output, relay outputs, and com-
munications. Isolation adds safety and avoids possible ground loops. The transducer excitation
output is isolated to 50V from signal ground.
Internal jumpers are used to select the signal range, communication type, and excitation level.
The transmitter configuration is specified by the model number on the transmitter label. A user
can reconfigure the transmitter by opening the case and moving jumpers.
Transmitter scaling is via serial connection to a PC using MS Windows based Instrument Setup
Software, which can be downloaded at no charge. The required transmitter-to-PC interface cable
is available for purchase.