Electrical parameters

Current consumption

 

Nominal

Max

Notes

General currents

Standby current
(12V & V+ ON)

13.22 mA

13.23 mA

Current after SerialClose()
has been called

Standby current
(12V & V+ OFF)

63.22 mA 64.71 mA
V+ Output (Sensor 1 & 2)   5 A Total  
12V Output (Sensor 1 & 2)   5 A Total  
V+ Input   10 A  
12V Input   10 A  
Bus Connector, V+   6 A  
Bus Connector, 12V   6 A  

RS-232 and RS-485 current consumption for both channels1
(12V & V+ ON)

Idle current

12.96 mA

12.96 mA

After SerialOpen()
has been called

Idle current (receive only)

13.52 mA

14.84 mA

After SerialOpen()
in receive-only mode

Active current (RS-232)

15.18 mA

16.26 mA

Active RS-232 command

Active current (RS-485)

15.63 mA

16.77 mA

Active RS-485 command (no termination resistors)

RS-232 and RS-485 current consumption for both channels1
(12V & V+ OFF)

Idle current

63.3 mA

63.8 mA

After SerialOpen()
has been called

Idle current (receive only)

63.5 mA

65.5 mA

After SerialOpen()
in receive-only mode

Active current (RS-232)

65.5 mA

67.4 mA

Active RS-232 command

Active current (RS-485)

65.9 mA

67.9 mA

Active RS-485 command (no termination resistors)
Line load currents
RS-232 line load 2 mA
per load		 –

Average expected increase in drawn current per RS-232 line connected in idle or active modes (no extra current in standby mode).

Both TX and RTS are considered to be RS-232 loads.
RS-485 line load2 40 mA3 77 mA4 This extra current is only present when actively transmitting

1 All currents are measured with no loads connected.

2 The RS-485 transmit pair is disabled when not transmitting in order to save power. Higher value resistors can be used to save power dependent upon the application. For many applications, especially with shorter cable runs, no load/termination resistors will be needed.

3 Single 100 Ω load between transmit lines. Two 100 Ω resistors (one on each end) is the maximum recommended loading. Removing any termination resistance should dramatically decrease current consumption during transfer of data.

4 The RS-485 interface is protected against short circuits via a 44 Ω resistance making this the maximum current possible even during short circuit. This resistance is part of the ESD protection circuitry and will be present at all times; it shouldn’t affect normal circuit operations. RS-485 internal circuit diagram shows the circuit in detail.

 

Voltage specifications

Connection

Minimum
voltage1

Nominal
voltage1

Maximum
voltage1

Power supply, +12 V  connection

9 V DC

12 V DC

30 V DC
Pass through power, V+ connection 0 V DC or AC Resistive N/A

30 V DC or AC Resistive

 

RS-232 input threshold low

0.8 V

–

–

RS-232 input threshold high

–

–

2.4 V

RS-232 input absolute maximum2

–

±15 V

±18 V

RS-232 input resistance

3 kΩ

5 kΩ

7 kΩ

RS-232 output voltage swing3

±5 V

±5.4 V

–

RS-485 input (differential)

200 mV4

–

6 V

RS-485 output (differential)

1.5 V (at 50 Ohms)

–

–

 

SDM lines (high level)

4.5 V

5 V

5.5 V

SDM lines (low level)

0 V

–

0.7 V

1 Voltage values are DC except for V+ which can handle AC or DC voltages.

2 It is NOT recommended that the user run their SDM‑SIO2R at maximum ratings for extended periods of time.

3 Assuming a worst case 3 kΩ load.

4 It is not recommended that the user allows such low input voltages as there will be an increased chance that external noise may cause errors in the incoming data.