LINUX
Driving the Onsala 20m via CANopen
The old control system used GBV 5410 amplifiers and KSY 548.30-1 motors (0.51 Nm/A) to drive the antenna via an analog output signal in the range of ±5000 DAC units from the digital control loop. The DAC signal yields a voltage ±10V at 16bit resolution (i.e. 10V/32768). The amplifier produces 6A per 5V.
The new system uses DSM 4-11.1 motors from SAD GmbH with a rated current of 4.9A and rated torque of 3.7Nm (i.e. 0.7551 Nm/A). They are driven by tendo DD4 servo amplifers from Mayr GmbH (now Pilz). The current output from the amplifiers is (rated current)\*(setpoint/1640). We get
(new setpoint) = (old DAC unit)*(10.0V/32768)*(6A/5V)*(0.51Nm/A)*(4.9A/3.7Nm)*(1640/4.9A)
= (old DAC unit)*0.0828
The four amplifiers in azimuth and elevation are connected via CANbus as nodes 10-13 and 14-17, respectively, to our VMEbus crate running ELinOS. The VMEbus system is equipped with a M65 CANbus interface from MEN GmbH and the corresponding CANopen Driver Interface System (MDIS4) for M65/P5. The M65 module has one single CANbus port. The master (VMEbus) is supposed to be node 1 on the bus. The baudrate used is 500 kb/s.
The amplifiers need to be configured once with correct node numbers and a rated current of 4.9A and max current of 9.8A through a PC based configuration utility.
In the following we’ll use xx for the (hex code) for the slave node
(0x0a - 0x11) and n is the number of the slave (0-7). The following
PDO setup is to be used:
- TPDO n on master ↔ RPDO 1 on slave n to set control word on amplifier(s)
- TPDO n+8 on master ↔ RPDO 2 on slave n to set setpoint in digital current mode
- RPDO n on master ↔ TPDO 1 on slave n to read status word of amplifier(s)
RPDO 1 for the control word is already set up by default: cobId
0x200+xx, 16 bit word at index 0x6040. Also, TPDO 1 on the slaves is
ready to be used (cobId 0x180+xx, 16 bit word at index 0x6041).
PDO 32 on the slaves is what we need as RPDO 2 for the setpoint (cobId
0x300+xx, 32 bit word at index 0x2060):
- SDO write to node: index
0x2601, sub 0, 1 byte: 32 (dec) (to select PDO 32 as RPDO 2)
In addition the following configuration is required on each slave during startup or error recovery.
- SDO write to node: index
0x6040, sub 0, 1 byte:0x80(to clear error conditions) - SDO write to node: index
0x6040, sub 0, 1 byte:0x0F(to enable and activate) - SDO write to node: index
0x6060, sub 0, 1 byte:0xFD(to configure digital current mode)
To set up the corresponding PDOs on the master we do the following (for each node):
- SDO write to master: index
0x1400+n, sub 1, 4 bytes:0x80000000(reset of RPDO node) - SDO write to master: index
0x1800+n, sub 1, 4 bytes:0x80000000(reset of TPDO node) - SDO write to master: index
0x1808+n, sub 1, 4 bytes:0x80000000(reset of TPDO node + 8)
Now, we are ready to configure the cobId’s of our slave nodes:
- SDO write to master: index
0x1400+n, sub 1, 4 bytes:0x180+xx(TPDO 1 cobId of node) - SDO write to master: index
0x1800+n, sub 1, 4 bytes:0x200+xx(RPDO 1 cobId of node) - SDO write to master: index
0x1808+n, sub 1, 4 bytes:0x300+xx(RPDO 2 cobId of node)
We need a mapping into the process image of the master, so that we can access inputs and outputs from our C application (loop.c):
- map TPDO n to index
0x6100(16 bit output, control word) - map TPDO n+8 to index
0x6120(32 bit output, setpoint) - map RPDO n to index
0x6300(16 bit input, status word)
Finally, we start monitoring of the slaves by the master:
- SDO write to master: index
0x1f80, sub 0, 4 bytes:0x00000001(enable NMT master) - SDO write to master: index
0x1f81, subxx, 4 bytes:0x00000001(assign slave, for each node!) - SDO write to master: index
0x1f82, sub 128, 1 byte: 5 (put all slaves into operational state)
Resulting PDO setup on slaves and master
| Slave setup | ||||
|---|---|---|---|---|
| Index | Sub | Value | Description | Comment |
0x2600 |
selection | RPDO 1 | ||
| 0 | 1 | receive control word | default setup | |
0x1400 |
communication parameter | |||
| 1 | 0x200 + xx |
cobId | default setup | |
0x1600 |
mapping parameter | |||
| 1 | 0x6040 00 10 |
index 0x6040, sub 0, 16 bit |
default setup | |
0x2601 |
selection | RPDO 2 | ||
| 0 | 32 | receive setpoint | requires configuration | |
0x1401 |
communication parameter | |||
| 1 | 0x300 + xx |
cobId | default setup | |
0x1601 |
mapping parameter | |||
| 1 | 0x2060 00 20 |
index 0x2060, sub 0, 32 bit |
default setup | |
0x2a00 |
selection | TPDO 1 | ||
| 0 | 1 | send status word | default setup | |
0x1800 |
communication parameter | |||
| 1 | 0x180 + xx |
cobId | default setup | |
0x1a00 |
mapping parameter | |||
| 1 | 0x6041 00 10 |
index 0x6041, sub 0, 16 bit |
default setup | |
| Master setup | ||||
| Index | Sub | Value | Description | Comment |
| send control word | TPDO 1-8 | |||
0x1800 + n |
communication parameter | |||
| 1 | 0x200 + xx |
cobId | requires configuration | |
0x1a00 + n |
mapping parameter | |||
| 1 | 0x6100 n 10 |
index 0x6100, sub n, 16 bit |
requires configuration | |
| send setpoint | TPDO 9-16 | |||
0x1808 + n |
communication parameter | |||
| 1 | 0x300 + xx |
cobId | requires configuration | |
0x1a08 + n |
mapping parameter | |||
| 1 | 0x6120 n+8 20 |
index 0x6120, sub n+8, 32 bit |
requires configuration | |
| receive status word | RPDO 1-8 | |||
0x1400 + n |
communication parameter | |||
| 1 | 0x180 + xx |
cobId | requires configuration | |
0x1600 + n |
mapping parameter | |||
| 1 | 0x6300 n 10 |
index 0x6300, sub n, 16 bit |
requires configuration |