ICC ETH-1000, Инструкция по эксплуатации

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11.12.1.2 Modbus/TCP Server
11.12.1.2.1 Overview
The gateway supports Schneider Electric’s Modbus/TCP server protocol, release
1.0. The gateway is conformance class 0 and partial class 1 and class 2
compliant, and allows up to 8 simultaneous Modbus/TCP server connections
(sockets). Other notes of interest are:
•
Supported Modbus server functions are indicated in Table 10.
Table 10: Supported Modbus/TCP Server Functions
Function
Code
Function Modbus/TCP Class
01 Read coils 1
02 Read input status 1
03 Read multiple registers 0
04 Read input registers 1
05 Write coil 1
06 Write single register 1
15 Force multiple coils 2
16 Write multiple registers 0
•
Database data can be accessed as either holding registers (4X references)
or input registers (3X references). Refer to 11.12.1.2.2.
•
Specific bits within the database can be accessed as either coils (0X
references) or discrete inputs (1X references).
•
Configuration tip: Improved network utilization may be obtained by
appropriately grouping contiguous register assignments in the database. In
this way, the “read multiple registers”, “read input registers” and “write
multiple registers” functions can be used to perform transfers of larger blocks
of registers using fewer Modbus transactions compared to a situation where
the read/write registers were arranged in an alternating or scattered fashion.
•
The “unit identifier” (UI) field of the request packets is ignored.
•
The socket timeout time is determined by the “timeout” setting on the web
server’s “Modbus” tab or via the “timeout” setting of the protocol selection
group in the configuration utility (refer to section 8.7.12.1.) This means that if
a particular open socket experiences no activity for more than the timeout
time setting, then the gateway assumes that the client or network has
experienced some sort of unexpected problem, and will close that socket.
•
Because the socket timeout determination is performed on a per-socket
basis, note that a certain degree of caution must be exercised when using
the network timeout feature to avoid “nuisance” timeouts from occurring.
Specifically, do not perform inadvisable behavior such as sending a request
from the master device to the gateway, and then closing the socket prior to