User`s manual

Western Reserve Controls, Inc. 1782-JDC User’s Manual

delimiter. The response is only updated when the delimiter is received or a buffer overflow

occurs. Every time the buffer is updated (e.g. the delimiter received or an overflow

condition) the record number will be incremented. The data is only valid up to the received

delimiter in your memory map. Data after the received delimiter may contain invalid data.

3. Direct the master to begin polling the JDC. Once the first delimiter is received, the

master’s memory will reflect data received by the JDC. The data returned will have the

following pattern:

Table 2-2 DeviceNet Consume Assembly / Serial Transmit Data String

BYTE MEANING

Byte 1 Record Counter

Byte 2 Serial Port Status

Byte 3 String Length (number of data bytes)

Byte 4 ASCII Character 1

….

Byte 23 ASCII Character 19

….

Byte 127 ASCII Character 124

The status/error byte represents the status of the ASCII data record received from the ASCII

device. This byte is defined as follows:

Table 2-3 Serial Receive Status/Error Byte

Byte Value Meaning

0 No error

1 Buffer Overflow

2 Parity Error

3 Buffer Overflow and Parity Error

2.6 How to Write Serial Output Data to the JDC

1. Set up the transmit size of your connection to equal the buffer size of the ASCII transmit

buffer plus 2. (Default is 22 bytes)

2. Map the IO transmit data of the JDC. The first byte of the JDC’s IO transmit array is the

record number. This value should be set to 0 at the beginning of communications. The

second byte is a length indicator, followed by the number of data bytes. The ensuing bytes

are the data that you wish to send to the JDC. If the length is set to 0 the JDC will send