Can you describe more detailed your setup? Are the 2 Wavcom modems connected together with their UARTs??
How do you transmit data between the modems? TCP/IP? Data call?
It can’t loose it over the air… This setting is a UART setting and if both modems are connected to a PC the PC has to have a matching the UART setting to communicate with the connected modem. But the port setting should have no further significance once the data is received by the modem…
Beside the PC there is a Fastrack modem with firmware v6.41. The PCÂ´s serial COM interface is opened with 7E1. Parity check is enabled. The FastrackÂ´s UART is set to 7E1 by AT+ICF=5,1
The other modem is an Integra M2106B with firmware v6.55. This is implemented in an industrial measuring device. Both UARTS (M2106B and measuring device) are set to 7E1.
The problem occurs during GSM-CSD communication.
This application has been working well since many years as long as we have used firmware v6.41 or lower in the M2106B. Beside the PC we could use any PSTN modem and even Wavecom Fastrack with firmware v6.41 for reading out the measuring device.
If I use firmware v6.55 in the M2106B, data transmission from PC to the measuring device is ok. The measuring device answers, but the answer can not be received by the read-out software on the PC as long as the parity check is enabled. If I disable the parity check on the PC, data transmission is possible in both directions.
In a second test, I used a Fastrack v6.55 beside the PC and a M2106B v6.41 in the measuring device. In this case, the characters transferred from PC to the measuring device are received with invalid parity flag.
Because of these results I guess, that the PSTN modems and the Wavecom v6.41 expects that the parity flag is transferred over the air (as a “8th data bit”) and transparently forwarded to the UART. In opposite to this the Wavecom v6.55 seems to delete the 8th bit in characters sent over the air!