Siko MSA501, Руководство пользователя

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Communication via
CAN bus (CANopen)
MSA501
Date: 12.10.2018 Art. No. 88734 Mod. status 330/18 Page 14 of 51
5.3 Process data exchange
5.3.1 Transfer of process data objects (PDO)
Process data objects (PDO) serve for fast exchange of process data. A maximum of 8 bytes of
user data can be transferred in a PDO. The MSA501 supports the Transmit PDO services TPDO1
and TPDO2 according to CiA DS-301 and CiA DS-406. The data content can be adjusted
individually via variable mapping.
5.3.1.1 Transmit PDO (from the MSA501 to the master)
PDO transfer from the display to the bus master (TPDO) can be initiated as a result of various
events:

asynchronous, controlled by an internal device timer

synchronous as a response to a SYNC telegram

as a response to an RTR message
When delivered, TPDO1 and TPDO2 are generated from the position value and the velocity
value. The transfer behavior of TPDO1 is determined via the objects 1800h, 1A00h and 6200h
and is assigned to asynchronous transmission. TPDO2 is defined via the objects 1801h and
1A01h and serves synchronous transmission.
The structure of the messages is shown in Table 12 , with variable and changeable mapping
(see chapter 5.3.1.2 Variable TPDO mapping ).
COB-ID Process data in binary code
Byte 0
(LSB)
Byte 1 Byte 2 Byte 3
(MSB) Byte 4
(LSB) Byte 5
(MSB)
TPDO1
180h + Node-ID Position value Velocity value
TPDO2
280h + Node-ID
Table 12: TPDO message
Asynchronous data transmission (TPDO1)
If a TPDO1 is to be sent cyclically, then the cycle time must be entered in milliseconds into
object 1800h, sub-index 05h. The TPDO1 will not be sent if the value 0 ms is written. The
function is disabled. The minimum value to be set is 1 (= 1 ms). Alternately, the value can
also be written into the permanently internally linked object 6200h.
Synchronous data transfer (TPDO2)
As delivered, the device responds to every SYNC message received with the output of the
TPDO2 message. 1h is entered for synchronous transmission in object 1801h, sub-index 02h.
If a value n between 1d and 240d (= F0h) is entered, the device will respond to every nth
SYNC message.