JD2D3-CDS-6F Digi International, JD2D3-CDS-6F Datasheet - Page 46

• Manufacturer Part Number: JD2D3-CDS-6F
• Description: Interface Modules & Development Tools RS-232 Cable 6 ft. Sub straight through
• Manufacturer: Digi International

Specifications of JD2D3-CDS-6F

• Interface Type: RS-232
• Product: Interface Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9XTend™ RS‐232/485 RF Modem ‐ Product Manual v2.x4x [2007.01.04]
4.5.2. API Types
Checksum
RF Modem Status
Data bytes that need to be escaped:
Note: In the above example, the length of the raw data (excluding the checksum) is 0x0002 and
the checksum of the non-escaped data (excluding frame delimiter and length) is calculated as:
0xFF - (0x23 + 0x11) = (0xFF - 0x34) = 0xCB.
To test data integrity, a checksum is calculated and verified on non-escaped data.
To calculate: Not including frame delimiters and length, add all bytes keeping only the lowest 8
bits of the result and subtract from 0xFF.
To verify: Add all bytes (include checksum, but not the delimiter and length). If the checksum is
correct, the sum will equal 0xFF.
Frame data of the UART data frame forms an API-specific structure as follows:
Figure 4‐05. UART Data Frame & API‐specific Structure:
The cmdID frame (API-identifier) indicates which API messages will be contained in the cmdData
frame (Identifier-specific data). Refer to the sections that follow for more information regarding
the supported API types. Note that multi-byte values are sent big endian.
API Identifier: 0x8A
RF modem status messages are sent from the modem in response to specific conditions.
Figure 4‐06. RF Modem Status Frames
Example - Raw UART Data Frame (before escaping interfering bytes):
0x7E 0x00 0x02 0x23 0x11 0xCB
0x11 needs to be escaped which results in the following frame:
0x7E 0x00 0x02 0x23 0x7D 0x31 0xCB
© 2007 MaxStream, Inc.
• 0x7E – Frame Delimiter
• 0x7D – Escape
• 0x11 – XON
• 0x13 – XOFF
Start Delimiter
Start Delimiter
(Byte 1)
0x7E
0x7E
MSB
Length
MSB
(Bytes 2-3)
LSB
Length
API Identifier
0x8A
LSB
API Identifier
API-specific Structure
0 = Hardware reset
1 = Watchdog timer reset
cmdID
Frame Data
Identifier-specific Data
API-specific Structure
Status (Byte 5)
cmdData
Frame Data
(Bytes 4- n)
Chapter 4 ‐ RF Modem Configuration
Identifier-specific Data
Checksum
1 Byte
cmdData
(Byte n + 1)
Checksum
1 Byte
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