CANopen output

CANopen sensors send the measured angle or acceleration with a TPDO message.

The Process Data Object(PDO) protocol is used to process real-time data among various nodes. You can transfer up to 8 bytes (64 bits) of data per one PDO either from or to the device. One PDO can contain multiple object dictionary entries and the objects within one PDO are configurable using the mapping and parameter object dictionary entries.

There are two types of PDO transmission:

1. Synhornous transmission
2. Event-driven transmission (default for DIS sensors)

The output format is explained in each sensor datasheet as below:

CANoutput = 100*α   (α is the angle in °)

For example, here you see 2 TPDO messages

The mapping of both TPDO messages are defined in the manual:

The TPDO1 Message 59 00 37 00 should be translated as 

X output = 00 59h = 89d, which means +0.89°

Y output = 00 37h = 55d, which means +0.55°

The negative numbers are represented with two's complement.

For example, -56° will be sent with a hex number: FFC8h

56d = 0000 0000 0011 1000b

-56d = 1111 1111 1100 0111b + 1 = 1111 1111 1100 1000b = FFC8h

CANopen Safety output

CANopen Safety sensor sends the measured angle or acceleration with both SRDO message and the TPDO message. SRDO is the reliable safety message, TPDO message is not advised to be used.

In the picture above, message 101 and 102 are the SRDOs, and 181 is a TPDO message.

Message 101 is the normal format, while 102 is the inversed format. Customers should compare these messages in order to check the sensor output is safe.
output FFFDh = -3d, which means the measured angle is -0.03°.

The CANopen safety sensor is in default in boot-up mode when you first connect the sensor to the CAN bus. The sensor sends only a heart-beat message with "00" indicating the NMT state. You will not receive any SRDOs until you set the sensor to "operational" mode.

You can use the attached excel for translating the output.