Perle Systems Sds4 Manuel d'utilisateur télécharger pdf (Page 422)

Utilities 421

API I/O Access Over TruePort

You can access IOLAN I/O data through TruePort using the Perle API. The API uses the

command/response format. See the

ioapiotp.c sample program, found on the product CD-ROM,

for an example implementation.

API Request Format

All data in the Request must be sent as a single write to the COM port. The API command takes the

following format:

API Response Format

The API command takes the following response format:

Number of Bytes Value

1 Function Code (in hexadecimal):

z 01—Get read/write boolean register

z 03—Get read/write register

z 04—Get read only register

z 15—Set read/write boolean register (0x0F)

z 16—Set read/write register (0x10)

2 Starting register number (see A4/T4 Registers , A4D2/A4R2 Registers ,

or D4/D2R2 Registers for this value).

2 Number of registers to act on starting from the register defined in byte

2 above.

n Data for write. Some values must be read/written as a unit consisting of

2 consecutive registers. If the request is to write, the data to write

follows the number of registers. If accessing registers consisting of 2

bytes or 4 bytes, the data is in big endian (network order) format.

Number of Bytes Value

1 Function code of request if no error. Most significant bit will be set if

an error occurred.

1 Length of data in response if no error occurred. If an error occurred, the

byte will contain the error code (see the

Error Codes table below).

n Data response for request (the number of bytes is dependent on the

number and type of registers requested). If the request returns 2 or 4

byte values, it will be in big endian (network order) format. If the

request returns boolean values, the least significant bit (bit 0) represents

the first value requested and bits 1 to 7 represents subsequent boolean

values. If more than 8 boolean registers are requested, they are returned

in successive bytes.

1 2 ... 417 418 419 420 421 422 423 424 425 426 427 ... 459 460

Pas de commentaire

Perle Systems Sds4 Manuel d'utilisateur Page 422