A point’s pn number indicates the Modbus register number the point is accessed with. Similarly, a point’s sn number indicates the ASD register that the point refers to. Each ASD channel (A, B, and C) has its own independent list of points.

A point’s value contains the value of the register referred to by its sn number. Via a service called data mirroring, point values are constantly being updated via communication with the connected drives and maintained locally within the interface itself. This greatly reduces the Ethernet network’s request-to- response latency time, as requests (read or write) can be entirely serviced locally, thereby eliminating the time required to execute an on-demand ASD data transaction.

Besides data mirroring, another advantage afforded by the ability to map any ASD register to any Modbus register is the capability of data reorganization. Data reorganization allows the grouping of ASD registers into more logical or efficient patterns to suit a given application. Because the Ethernet network client never “sees” the true ASD register numbers, the point mapping assignments can be determined by any user-defined criteria. For instance, several disjoint ASD status registers (sn numbers) can be assigned to contiguous Modbus registers (pn numbers), thereby allowing the status items to be read with a single “read multiple register” transaction. Data reorganization can therefore enhance network efficiency by minimizing the total number of data transactions required.

A point’s name is simply a descriptive title assigned to the point to more easily identify the point’s function during device configuration and monitoring. This name is only accessible via the HTTP (web browser) interface.

Refer to section 13 for specific information related to configuring points.

12.3.2 Direct (Implicit) Mapping

The ETH-100 also provides direct access to the attached ASDs by allowing circumvention of the point database. Modbus TCP/IP holding registers (04 registers) that are not defined as points are mapped to the numerically corresponding ASD registers (also referred to as “communication numbers” in Toshiba documentation) with a direct 1-to-1 relationship. The relationship between Modbus TCP/IP holding registers that are not defined as points and their ASD register counterparts is as follows:

Modbus TCP/IP holding register = ASD register + 1

This means that in order to access a Toshiba drive register, simply add 1 to its register number and access that Modbus TCP/IP holding register. The reason for this offset is due to the fact that Toshiba drive registers begin at number 0, while Modbus holding registers must begin at number 1. Because this access method bypasses the point database’s explicit mapping definitions, it is referred to as “direct” or “implicit” mapping. Also, because direct mapping cannot take advantage of the point database’s data mirroring service, Ethernet

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