SSD Series – Riedon™ Digital Current Sensor with RS485/MODBUS Interface by Bourns

SSD Interface Manual

Name

Size

Units

Range

Current

Signed int32

1 mA

± 20 X Nominal

Temperature

Signed int32

0.1 °C

-40 °C to +125 °C*

Bus Voltage (Vbus)

Signed int32

1 mV

±1200 VDC

Coulomb

Signed int64

C (A•s)

± 260

Power

Unsigned int32

0.1 W

0 to 232

Energy

Unsigned int64

W•h

0 to 260

*Values outside specification are reported.

This sensor is software selectable between plain RS485 or MODBUS RTU. If changing from one format to the other, set SET MODE

configuration bit2 to the correct value (page 16), save settings to EEPROM (RESET COMMAND page 15), then reboot the sensor. It

will boot to the correct format.

STANDARD RS485

Default COM Settings – 19200 baud, 8 bits, No Parity, 1 Stop (no echo)

Message Format

:1XX1234<cr>

All SSD commands begin with a colon ‘:’

Then the sensor address (1 to 255)

Then a two letter command

Then an optional value

Command is terminated with a <cr>

Line feeds <lf> are ignored

NOTE: In RS485 mode, the SSD sensor does not check to see if bus is free when sending data.

Use caution when enabling automatic sending modes.

MODBUS RTU

Default COM Settings – 19200 baud, 8 bits, No Parity, 2 Stop

MODBUS registers larger than 16 bits have a little-endian byte swap format.

MODBUS is a purely master / slave protocol with the SSD sensor as a slave device.

Specifications are subject to change without notice.

Users should verify actual device performance in their specific applications.

The products described herein and this document are subject to specific legal disclaimers as set forth on the last page of this document, and at www.bourns.com/docs/legal/disclaimer.pdf.