Host Protocols Direct Protocol PROTOCOL class SET SERIAL PARAMETERS
September 3, 2025 at 8:28 AMSET SERIAL PARAMETERS instruction
The SET SERIAL PARAMETERS instruction is used to change the communication parameters over the Serial host interface.
INS value
INS = 11
Command
| Field | Value | Explanations |
|---|---|---|
| CLA | 00 |
Class = PROTOCOL |
| INS | 11 |
Instruction = SET SERIAL PARAMETERS |
| Data | Bitrate, on 4 bytes | See below |
Response
| Field | Value | Explanations |
|---|---|---|
| CLA | 00 |
Class = PROTOCOL |
| STA | 00 |
Success |
| Data | (empty) |
Supported bitrates
The host must specify the desired bitrate on 4 bytes, in MSB order. Only the following bitrates are supported1:
| Bitrate | Value | Remark |
|---|---|---|
| 38400 | 00 00 96 00 |
Startup value |
| 115200 | 00 01 C2 00 |
|
| 230400 | 00 03 84 00 |
|
| 460800 | 00 07 08 00 |
|
| 921600 | 00 0E 10 00 |
1 They are supported by the firmware. This does not imply that they are supported by the hardware (RS-485 drivers and links are likely to have a limited bandwiths, but RS-232 and even RS-TTL interfaces may be unable to convey the highest bitrates without errors). Always respect the limits specified in the datasheet of every product.
Implementation details
The device applies the new bitrate only after having (positively) answered to the command over the previous bitrate.
Pay attention that the command is executed even if it comes from another interface than the Serial!