08.2012 Technology Option F01
Siemens AG 6SE7087-6QX70 (Version AN)
SIMOVERT MASTERDRIVES Compendium Motion Control 9-73
→ The contents of the PROFIBUS message frame for defining the MDI
block are as follows:
Word 6 = 5B 21 (hex) ;5B (hex) = 91 (decimal) = "relative traversing"
;(in incremental dimensions) 21 (hex) = 33
;(decimal) = "30 % acceleration/deceleration"
Words 7 and 8
= FFFF CFC7 (hex)
;-12.345° = -12345 LU = FFFF CFC7 (hex)
Words 9 and 10
= 0000 4A38 (hex)
; 190°/min = 190 000 LU/min ==> input value
;in [10 LU/min] = 19 000 (decimal) = 4A38 (hex)
A simple traversing operation is started as follows:
♦ Drive ON (OFF1=1; inverter enable [ENC] can remain permanently
at "1"; [180])
♦ Select MDI mode [MODE_IN] = 3 [809.4]
♦ Wait for a mode checkback signal [MODE_OUT] [811]
♦ Set the start command [STA] to "0" [809.4]
♦ Wait for a start enable [ST_EN]
♦ Evaluate any warnings/faults (bits 3 and 7 in basic unit status word 1
[200], connector K0250 [510], parameter n540.26 [818])
♦ Initiate the start command (0 => 1 edge at [STA])
♦ The "function terminated" status bit [FUT] switches to "0" when the
start command is activated and switches to "1" when the movement
is finished or aborted in the event of a fault [811.4]. The [FUT] is a
reliable indication that the traversing movement is finished - even in
extremely short movements.
♦ The "destination reached, axis stationary" status bit [DRS] indicates
with a "1" signal that the drive has stopped in the "exact stop
window" [811.4]. The exact stop window is defined by machine data
MD16 and MD17.
You can use the velocity override [823.3] to modify the traversing
velocity defined in the MDI block by a factor of 0 ... 255 %, e.g. during
commissioning. The velocity override can also be varied in motion and
defined, e.g. via U708 [809.1], over a field bus or from an analog input
(the source connector can be selected with U709 [809.1] or U530
[809.7]).
You will find detailed information on "MDI mode" in the chapter of
the same name in the Function Description of manual /1/. The
"MDI on the fly" function is described there. With MDI on the fly,
the MDI traversing record is supplied via MDI traversing record 0.
The difference to the "normal" MDI lies in the control through the
toggle bit, i.e. a flying change of MDI positioning is not performed
until a signal change has taken place at the toggle bit.
Start of the
traversing operation
Wait for the
checkback signal
indicating the end of
the traversing
operation
Velocity override
Further information
on MDI mode
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