Westermo TD-22 - Manual (Page 44)

45 6177-2203
Dial up with hardware signalling
Dial-up can be made by applying an external signal to the DTR-pin in the RS-232 contact. A typical
application is an alarm signal from a PLC.
The modem reacts on the first rising edge which means that one pulse is sufficient. The signal-level
should be in compliance with the RS-232 standard. If only a relay contact is available the DSR-pin
will provide a suitable voltage.
The modem does not have a redialling function. If necessary this must be handled by other
equipment connected. We advise the DCD signal to be used as a control indicating whether
connection was made or not.
AT&B1 Dial-up using DTR.
AT&D3 Hang-up if DTR goes low.
AT&Z0=nn The number to dial, nn, is stored in memory position 0.
Please also refer to “To use minicall”, as the minicall and the dial-up with hardware signalling can
be used together.
External signal