JVL MAC050 User Manual page 402

6.10
Changing baud rate
This section describes how to change between the baud rates supported by the motors
and modules in those cases where that is allowed.
At every start-up, both the basic motors and the MAC00-xx modules start at a speed of
19200 bits per second on both the FastMac channel and the MacTalk channel. Note that
the speed will not be saved in the motor or module flash memory, which ensures that
another motor or module can be easily interchanged.
The speed can then be changed to 57600 baud, but can not be changed back to 19200
baud without resetting the motor and module.
At the time of this writing, only MAC800 and the MAC00-FCx modules support 57600
baud.
To change the speed on the FastMac channel with intelligent modules follow these steps:
1: The basic motor must be set to passive mode (the mode register, register 2, must be
zero).
2: Send a special command to the module through its Fieldbus interface. For the
MAC00-FCx this is CANopen®, and a command is sent by writing a value via SDO
to object 2010 hex.
When the command number 5 is written to object 2010, the module will perform the
steps to change the baud rate in both the module and the basic motor, but only on the
FastMac channel – the MacTalk channel is unaffected. This change of baudrate will last
about eight millisecond, during which no other communications can occur between the
module and the motor.
To change the speed on the MacTalk channel follow these steps:
1: Set the motor to Safe Mode (the mode register, register 2, must be 15).
2: Send a special command telegram of
AA
<
FF
<
bitwise inverted byte. E.g.
3: Wait for 10 millisecond for a reply. If a reply of
means the motor can not change to the new baudrate, probably because it is not in
Safe Mode or if some other error has occurred. If no reply is received within the 10
ms, it can be assumed that the motor has changed to 57600 baud, and further com-
munication can continue at the higher speed.
General notes on the MAC00-xx interface modules operation
Modules generally have two functions. One is to translate between an industrial fieldbus
like CANopen®, DeviceNet, ProfiBus and high speed RS-485. The other is to execute
small userdefined programs much like a traditional PLC. During execution, the modules
communicate extensively with the basic motor over a serial connection that is typically
much slower than the fast fieldbusses.
The following points are important to consider to understand the limitations regarding
module capabilities:
- When writing a value to the basic motor via an intelligent module, the write opera-
tion is queued up in a buffer in the module, which can typically hold up to 16 opera-
tions. The values are written to the motor at the speed of the FastMac channel, either
19200 or 57600 baud. The FastMac protocol has some overhead, and the basic mo-
tor only performs operations once per sample period, so a full register write (or
read) can take up to almost 20 millisecond at 19200 baud. The normal time is 10.5
to 15 millisecond for a single register transfer.
398
Serial communication
where the FF
>, < ><
00 to address any motor or the address of a specific motor followed by a
>< >
JVL A/S - User Manual - Integrated Servo Motors MAC050 - 4500
58 58
< > <
00 is the motor address. As usual this can be
>
04 FB .
< > < >
<
58 FF 00
> < > < > < > <
11 11 11 is received, it
>< >< >
AA
>