ICC OPC-PRT3, Инструкция по эксплуатации, Страница: 51 / 115

ICC
50
10 PROTOCOL-SPECIFIC INFORMATION
This section will discuss topics that are specific to each of the supported protocols.
10.1 Modbus/TCP
10.1.1 Overview
The interface card supports Schneider Electric’s Modbus/TCP protocol, release 1.0. The interface is
conformance class 0 and partial class 1 and class 2 compliant. Other notes of interest are:
•
Supports up to 8 simultaneous connections.
•
Modbus/TCP should not be confused with Modbus (serial) over TCP. Modbus over TCP is not
compatible with Modbus/TCP and is not supported.
•
The driver can be configured to detect a timeout (communication loss) and perform a timeout
action.
10.1.2 Unit ID
The “unit identifier” (UI) field (also known as the slave ID and node ID) of the request packet is ignored
and is echoed in the response. Any Unit ID value is allowed.
10.1.3 Functions
The supported Modbus/TCP functions are indicated in Table 19.
Table 19: Supported Modbus/TCP Functions
Function
Code
Function
Modbus/TCP
Class
1 Read coils 1
2 Read input status 1
3 Read multiple registers 0
4 Read input registers 1
5 Write coil 1
6 Write single register 1
8 Diagnostics (subfunction 0 only) -
15 Force multiple coils 2
16 Write multiple registers 0
10.1.4 Holding & Input Registers
The inverter registers by default are mapped as both holding registers (4X) and input registers (3X) and
are accessed by using the inverter register numbers described in section 4.1. Examples are shown in
Table 20.
Table 20: Modbus Register Examples
Function Code
Holding/Input
Register Number
S05 (Frequency command) 1798
M09 (Output frequency) 2058
The 4X and 3X only serve as a naming convention for holding register and input register respectively,
and should NOT be included as part of the actual on-the-wire register number. To further clarify, Modbus
register 42058 is the same as Modbus holding register 2058. The same description applies to input
registers (3X).
For example, from a Modbus/TCP master’s point of view, in order to access the output frequency
(function code M09, register 2058) as a holding register, the Modbus/TCP master must execute the
Read Multiple Registers function code and target register 2058. This will similarly apply when accessing
an inverter function code as an Input Register.