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dc2227af

DEMO MANUAL DC2227A

aDDitional information

Operation in SIO Mode

The device can also operate in SIO mode. In this mode,

no IO-Link communication takes place either because the

master connected to the device is in the “Inactive” mode

and it only supplies power to the device, or because there

is no master connected to the device in which case the

device is powered by a 24V supply. In SIO mode, the

DC2227A reactsto the status of the light barrieras follows:

• If the light barrier is open, then drivers CQ1 and Q2

actively pull low. Since the onboard light bulb is con-

nected between Q2 and ground, it is therefore turned

off.

• If the light barrier is closed (by placing a piece of paper

in its gap), CQ1 and Q2 actively pull high and the light

bulb attached to Q2 turns on.

Temperature Sensor Configurations

In IO-Link mode, the DC2227A reports cyclically to the

master (and thus to the PC Control Tool) the temperature

measured by the on-board LTC2997. In order to measure

temperature the LTC2997 uses an NPN configured as a

diode. The NPN can be either on-chip, on PCB (Q1) or

remote. Refer to the Connectors and Jumpers section for

detailed information on how to choose the NPN.

Microcontroller ADC’s Offset Correction

The 12-bit ADC of the Atmel microcontroller samples

VPTAT outputs of the LTC2997 to report the temperature

in Celsius to the IO-Link master. The temperature is then

calculated using a ratiometric measurement. The µC’s

ADC is specified to have offsets from –40 to 40 LSBs.

The temperature equation is:

100

•T(°C)=

ADC7 –OFFSET

ADC4–OFFSET

• 45000 – 27315

ADC7 is the ADC’s code for the VPTAT output and ADC4

offset (in LSB) parameter that can be set using the control

tool (default is 0 LSB). In order to improve the accuracy

of the temperature reading, a calibrated thermometer can

be used to measure the temperature close to the LTC2997

and then the ADC Offset parameter can be set to the value

(after several tries) that minimizes the error between the

temperature reported by the Control Tool and that given

by the calibrated thermometer.

Event Generator

The DC2227A is also equipped with a pushbutton to

simulate events generated by IO-Link devices to inform

IO-Link masters of requests that require special attention.

Light barrier

The light barrier offers many ways to interact with the

device. It starts the device in COM3 mode if it is closed

during power-up or in COM2 mode if left open. In IO-Link

mode, its status is reported live on the PC control tool and

in SIO mode its status is directly coupled to the CQ1 and

Q2 drivers, thus allowing the user to operate the light bulb.

Light bulb

A 28V/100mA light bulb connects between Q2 and ground

and serves to show the high current driving capability of

the line drivers. It takes about 240ms to be turned on fully

bythepulsingmechanismoftheLT3669-2.Topreventdata

loss in IO-Link mode, driver Q2 is only enabled in between

IO-Link telegrams. To turn it on and off from the control

tool (in COM2 only) simply press the “Turn On” and “Turn

Off” buttons within the light bulb section. In SIO mode,

regardless on the IODD file chosen, the light bulb can be

switched on and off by interacting with the light barrier.