National Instruments FieldPoint FP-1300, Руководство пользователя

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Chapter 2 Installing and Configuring Hardware and Software
FP-1300 User Manual 2-14 ni.com
FP-1300 CAN Message Arbitration IDs
In the default mode, the FP-1300 configures the arbitration IDs of the CAN
messages that contain FieldPoint I/O channel data using the base arbitration
ID. Since the lower 8 bits are reserved for this purpose, a range of 255 IDs
is possible. The FP-1300 reserves the first two IDs (0 and 1—offset from
the base arbitration ID) for communicating configuration information with
the FP-1300 Configuration Utility. Arbitration ID offsets 2–255 are used
for transmitting I/O channel data. For example, if the base arbitration ID of
the FP-1300 is 0x300, arbitration IDs 0x300 and 0x301 are used by the
FP-1300 Configuration Utility. Arbitration IDs 0x302–0x3FF are used for
transmitting I/O channel data.
The FP-1300 allocates channels to the first arbitration ID beginning with
the first module and channel. Each analog channel uses 2 bytes of
arbitration ID. Each discrete channel uses 1 bit of arbitration ID. Therefore,
in a CAN message (8 data bytes) you can assemble a maximum of
four analog channels or 64 digital channels. The FP-1300 will not mix
input and output I/O channels in the same arbitration ID.
Note By default, the FP-1300 begins a new arbitration ID on a new module.
For example, a typical FP-1300 bank consists of the following I/O modules:
• Module 1: FP-AI-100 (8-channel analog input module)
• Module 2: FP-AO-200 (8-channel analog output module)
• Module 3: FP-DO-401 (16-channel discrete output module)
Assuming that the base arbitration ID is set to 0x300, the data IDs are
configured as shown in Table 2-3.
Table 2-3. FP-1300 Arbitration ID Configuration
ID Byte Module Channel Comment
0x300 Reserved for configuring the FP-1300 module using the FP-1300
Configuration Utility
0x301 Reserved for configuring the FP-1300 module using the FP-1300
Configuration Utility
0x302 0, 1 1 0 2 bytes per
analog channel
0x302 2, 3 1 1 2 bytes per
analog channel