Toshiba VF-A7 Manuel d'utilisateur télécharger pdf (Page 33)

10.8 Performance Tips

This section offers several configuration tips which can help to optimize the

performance of communications with the ETH-100 and attached drives.

1. Configure Modbus programmable pointer registers to also be drive scan

registers. In the example configuration shown in Table 3, Modbus registers

FC00 ~ FC07 are configured to point to the ASD scan registers. In this case, a

Modbus transaction beginning at address FC00 with a length of 8 can be

processed extremely fast. Of course, pointer registers can still be accessed if

they are not configured as scan registers, but the transactions are slower, as they

require transferring the request to the drive for processing.

Table 3: Efficient Scan/PPR Configuration

ASD Scan Registers Modbus Pointer Registers

FA01 Read FC00 FA02

FA00 Read FC01 FA01

FD00 Read FC02 FD01

FE01 Read FC03 FE02

FC90 Read FC04 FC91

FE03 Read FC05 FE04

FE42 Read FC06 FE43

FA22 Read FC07 FA23

2. Don’t leave a gap in the access sequence. For optimal network response,

make sure all of the pointer registers that you are going to access are also

configured to be ASD scan registers. The ETH-100 is most effective when all of

the pointer registers that are going to be accessed are also ASD scan registers.

In the example shown in Table 4, the high-speed processing of a Modbus register

read starting at register 0xFC00 with a length of 8 will be delayed by the necessity

to interact with the drive to obtain the values of drive registers 0xFC90 and

0xFE03.

Table 4: Inefficient Scan/PPR Configuration

ASD Scan Registers Modbus Pointer Registers

FA01 Read FC00 FA02

FA00 Read FC01 FA01

FD00 Read FC02 FD01

FE01 Read FC03 FE02

FC04 FC91

FC05 FE04

FE42 Read FC06 FE43

FA22 Read FC07 FA23

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Toshiba VF-A7 Manuel d'utilisateur Page 33