16 840Di Specific Data and Functions
16.2 Expanded message frame configuration (SW 2.2 and higher)
The drive data must be configured as additional process data on the drive with the exact meaning
in the exact order specified in Table 16-1.
Application example for system variables in a synchronized action:
Specific drive data
Smoothed torque setpoint (Mset)
Active power (Pact)
Smoothed torque-producing current Iq
Transfer of specific drive data can only take place if the following is applicable:
Standard message frame data + additional data v max. number process data.
Currently a message frame can contain up to 16 process data items (PDA1 to
The entire message frame with standard process data and additional process
data is transferred in a general system variable as an array of 16-bit integer
data words via:
MD 36730: DRIVE_SIGNAL_TRACKING[n] = 2
System variable: $VA_DP_ACT_TEL[n, a]
with n = index: 0,2,...15
a = machine axis identifier.
When using the system variable $VA_DP_ACT_TEL[n, a], it is only permissible
to use a constant as index n.
IDS=1 DO $AC_MARKER = $VA_DP_ACT_TEL[12, X]
The user must take the following points into account with regard to the data for-
mats of the process data stored in the system variables:
The process data are transferred in the message frame in the following for-
– unsigned 16-bit integer (UINT16)
They are stored in the system variables in the format
– signed 32-bit integer (INT32)
In the necessary format conversion, bit 15 of the unsigned 16-bit integer
PDA value is transferred to bits 16 to 31 of the signed 32-bit integer value in
the system variable.
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition