3.Group read and write registers together in the programmable pointer list and access them with separate Modbus commands. The ETH-100 can process read requests and write requests faster when they are grouped together rather than the master having to issue multiple transactions to access disjoint registers. This is especially true when the registers to be accessed are also configured as ASD scan registers. Pointer registers can be accessed in any combination of starting register and length. In the setup below, you would optimize ETH-100 efficiency by having two Modbus transactions: one read request with a length of 6 starting at register FC00, and one write request with a length of 2 starting at register FC08.

Table 5: Grouping Read and Write Registers In The PPR List

Modbus Pointer Registers

Modbus Pointer Registers

(Also configured to be ASD READ

(Also configured to be ASD

scan registers)

WRITE scan registers)

Register

Points To…

Register

Points To…

FC00

FE03

FC08

FA02

FC01

FE06

FC09

FA01

FC02

FD01

FC0A

 

FC03

FE02

FC0B

 

FC04

FC91

FC0C

 

FC05

FE04

FC0D

 

FC06

 

FC0E

 

FC07

 

FC0F

 

33