Siemens SINUMERIK 840D sl Function Manual page 169

Requirements
The following machine data must be set to the value 1:
MD36730 $MA_DRIVE_SIGNAL_TRACKING
Sequence
The values of the drive system variables of a link axis are provided in two steps:
1. The home NCU (that is, the NCU that is physically connected to the link axis) uses a
2. The interpolating NCU checks (e.g. in another synchronized action) the state of the link
Machine data for example
NCU1:
$MN_AXCONF_LOGIC_MACHAX_TAB[0] = "AX1"
$MN_AXCONF_LOGIC_MACHAX_TAB[1] = "AX3" ;*
; * When the axis that is not defined as a link axis is concealed,
; AX2 would be entered here.
$MN_AXCONF_LOGIC_MACHAX_TAB[2] = "AX4"
$MA_DRIVE_SIGNAL_TRACKING[AX2] = 1 ; Activation of provision of values
NCU2:
$MN_AXCONF_LOGIC_MACHAX_TAB[0] = "NC1_AX2" ; Link axis
$MN_AXCONF_LOGIC_MACHAX_TAB[1] = "AX1"
$MN_AXCONF_LOGIC_MACHAX_TAB[2] = "AX2"
Synchronized actions
NCU1:
; Static synchronized action transfers the drive variable cyclically
N111 IDS=1 WHENEVER TRUE DO $A_DLR[0]=$VA_CURR[AX2]
NCU2:
; Static synchronized action accepts the value from the link variable
; and triggers alarm 61000 if the current exceeds the limit of 23 A
N222 IDS=1 WHEN $A_DLR[0] > 23.0 DO SETAL(61000)
Extended Functions
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Several Operator Panels on Several NCUs, Distributed Systems (B3)
static synchronized action to cyclically read the information contained in the system
variables into a link variable (see 7.14.1). The link variable can also be accessed on the
interpolating NCU (in our example, NCU2).
variable and initiates the required response.
2.8 Cross-NCU user communication, link variables
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