Manual MCS-64 Page 9
3 CANopen
profile
3.1 The
PDOs
The status is sent constantly to the CAN controller. The TPDO1 is sent up to 320 times per
second. This has to cover all installed modules. With a 64 LDM installation this gives 5
measurement per second per LDM, a 32 LDM installation will give 10 measurements per
second per LDM. Speed could be increased with a 16 LDM installation to 20 measurements
per second per LDM (only possible with special firmware for Gateway).
The TPDO2 is sent every time a LDM finishes a filling cycle. It has the same format and
fields as the TPDO1 except it contains the DOSED NET weight.
The format of the TPDO1 and TPDO2 is:
32 bit
16 Bit
8 bits
8 Bit
Weight
Module Status
Module number
Gateway
State
The first field is a single precision float value containing weight information,
Gross or Net values if it is a TDPO1, and the Dosed NET weight if it is a TPDO2.
The next 16 bit field contains the module status as described below:
$0001 - Under range,
$0002 - Over range,
$0004 - Not within Zero range (not yet implemented, zero),
$0008 - Exactly zero,
$0010 - No motion, still stand, steady state,
$0020 - Tare set,
$0040 - Preset tare (0=tare is measured, 1=tare is set by user),
$0080 - Invalid weighing (wire-break, A/D ref. out of range),
$0100 - Set-point 0 (source>limit),
$0200 - Set-point 1,
$0400 - Set-point 2,
$0800 - Set-point 3,
$1000 - Filling in progress,
$2000 - Filling has completed.
$4000 - Average ready,
$8000 - Cold start.
Module number is the module (LDM) from which the data originates (0..63).
Gateway state is the state of the CANopen Gateway itself. This field is formatted as
follows:
2 bit
2 Bit
4 Bit
cmd resp reserved
“cmd” is a modulo-4 counter that increments every time a command is received i.e.
every time a SDO is received by the Gateway. If the completion of the SDO setting
requires communication with a LDM on the backplane the user can monitor the “resp”
field to determine when the LDM has acknowledged the command.
“resp” is a modulo-4 counter that increments when a command has been processed
(and a result can be fetched). If a SDO has been received, it indicates when the
Gateway has finished processing the SDO.
