ZiLOG
Register
S21
S22
S23
S24
S25
Range
Reserved
Reserved
Reserved
Reserved
0–255
S26
Reserved
S27
Reserved
S28
0–255
S29
0–255
S37
0–6
Z02205
Modem Controller
Table 4. Modem S-Registers (Continued)
Units
Description
Reserved Reserved
Reserved Reserved
Reserved Reserved
Reserved Reserved
seconds
During synchronous operation with the &Q1 command in effect, S-register S25 indicates
or 1/100 sec. the number of seconds after a telephone line connection is made before the modem
examines DTR. This register allows sufficient time to disconnect the modem from an
asynchronous terminal and attach it to a synchronous terminal. In the On-Line or
Command state during any mode of operation, changes in DTR for less than S25
hundredths of a second are ignored.
Reserved Reserved
Reserved Reserved
minutes
Terminal inactivity timeout. Hangs up the modem after S28 minutes if no characters are
received from the modem’s terminal. Default = 0
1/50th sec
code
Hook Flash On-Hook time. The amount of time in 20 millisecond units the modem will
leave the telephone on-hook while performing a hook-flash according to the “!” dial
string modifier. Default = 25 fiftieths of a second.
Sets the Highest Line Rate. This register determines the highest telephone line data rate
the modem will use when connecting with a remote modem. See “Setting the Highest
Line Rate” section on the following page. Default = 0.
PS001000-MOD0599
19