4.3.1 Maximum Telegram Length
According to the wM-Bus telegram format, a maximum length of 0xFF (255) bytes can be set in Length field (L-field). For L-field, count the Control field (C-field), Manufacturer ID (M-field), Address field (A-field) and Control Information (CI-field) in addition to the data length. Therefore, a maximum data length of 245 bytes is possible via telegram format.
In case of TX, send this maximum 245 data bytes (or less) that are already written to the
data buffer (g_wmbusDb).
In case of RX, there are some limitations because the complete telegram, including
general fields, data and CRCs of each block, are stored in the data buffer
(
g_wmbusDb). The limitation to the SRAM buffer is 282-bytes, and
this results in limitations of receivable data bytes. The limitation is higher in the
T-mode because 3-of-6 encoding is received in NRZ. The following table provides details
about the maximum telegram length.| Mode | Maximum RX Data |
|---|---|
| S | 238 bytes |
| T | 154 bytes |