Specifications

Section 2—Modbus Plus Overview Bulletin No. VVDED397044US R12/00

Command Semaphore December 2000

of the drive controller to the MODBUS port device by setting bits 8 and 15

of control word CMD to 1.

Among MODBUS PLUS devices, only one device can write to the drive

controller’s control words. If peer cop data is enabled within the drive

controller, it receives its peer cop data from a designated control device.

No other device can write to the control words, unless the drive controller

does not receive peer cop data within the designated time-out period, and

so falls into CNF fault mode. Once the drive controller receives peer cop

data again, it again rejects all message requests to write to the control

words. (See “Peer Cop” on page 43.)

If peer cop is disabled or the drive controller is in CNF fault mode, the first

device to write to control words 400, 401, and 402 via message handling

gains access to the control words, and no other devices can write to these

words. The controlling device releases control under any of these three

conditions:

• The control device writes a value of 1 to bit 8 of Word 400.

• The control device fails to send any read or write message to the drive

controller within the specified time-out period.

• The drive controller experiences a communications fault (CNF).

The times to update variables for 32 peer cop data processing operations

and for 32 global data transfers are as follows:

• Peer cop data processing, first three control variables: 15 ms

• Peer cop data processing, following 29 adjustment variables:

500 ms

• Update period of global data, first 14 variables: 15 ms

• Update period of global data, following 18 variables: 500 ms

CONTROL MODES

The ATV58 drive controller can be controlled in local mode via the

operator keypad or terminal, or remotely through the serial link.

The setpoints and control orders cannot be controlled separately.

The possible sources of control are:

• through hard-wired I/O points on the terminal strip

• through a keypad or computer connected to the drive controller

through its built-in MODBUS serial port