jhs@MITRE-BEDFORD.ARPA (07/23/87)
>> The connections you show are correct and should work fine (see below). Avatek 1200hc Modem pinout Atari 850 Serial Port #1 pinout My Pin I/O Function Hookup Pin I/O Function 2 In Transmitted Data (TD) <--- 3 Out Send Data 3 Out Received Data (RD) ---> 4 In Receive Data 5 Out Clear To Send (CTS) ---> 8 In Clear To Send (CTS) 6 Out Data Set Ready (DSR) ---> 6 In Data Set Ready (DSR) 7 Signal Ground <--> 5 Signal Ground 8 Out Carrier Detect (CD) ---> 2 In Carrier Detect (CRX) 20 In Data Terminal Ready (DTS) <--- 1 Out Data Terminal Ready (DTR) 22 Out Ring Indicator (RI) 7 Out Request To Send (RTS) Pin 22 on the modem and pin 7 on the 850 are not connected to anything. Note that the modem has 2 inputs and 5 outputs while the 850 has 4 inputs and 3 outputs (not including ground). >> This discrepancy is not a problem. You don't really need Ring Indicator at >> the 850, because the modem itself takes care of answering the phone, and >> you (the 850) find out about it when a carrier is received. This is >> usually more convenient than having to worry about Ring Indicator in >> software in the terminal. If you really need a Request To Send signal, >> most likely strapping Carrier Detect over there too will work fine. You >> normally wouldn't want to send anything unless you were receiving a >> carrier, would you? Modem Option Switch Settings (* indicates factory setting) >> These pretty much look OK too, with the exception(s) noted below. Switch Function UP DOWN 1 Data Terminal Ready DTR line signal *DTR forced on >> Forcing DTR on may make it hard to end a connection from the computer end, >> but shouldn't cause the symptom you mentioned. 2 Message Format *Displayed in words Displayed in numbers 3 Message display Messages not displayed *Messages displayed 4 Echo *Commands displayed Commands not displayed 5 Auto Answer Forced on *Disabled 6 Carrier Detect (CD) CD line signal *CD forced on >> My hunch -- the only thing I can come up with -- is that forcing this >> signal ON might intimidate the modem and make it unwilling to dial. >> I.e. the poor thing may be firmly convinced that it is already talking >> to another like-minded modem and it doesn't want to scare it (him? her?) >> away with a yukky touch-tone dialing sequence. 7 Clear To Send (CTS) CTS line signal *CTS forced on >> This signal may also confuse the modem but I'm betting on DCD as the >> culprit. 8 Command recognition Commands not recognized *Commands recognized I've played with the switch settings to no effect and have left them in the factory default position. I have 2 different modem programs for the 850 interface that run at 1200 baud and are Hayes compatible. In both case the programs will print that they're dialing the phone number but nothing happens, there are no touch tones dialed. The phone system does work normally for voice. >> If my suggestion doesn't work, I think you have a defective modem. >> You should attempt to get a replacement and try it out. >> Hmm... the only other thing I can think of is that the modem is connected >> to the phone line backward. And I am guessing here, because while I know >> that Ma Bell phones refuse to send Touch Tones if the DC polarity is >> wrong, I DON'T know that the Avatex does this too. But it might! >> If you have a phone jack where a genuine Ma Bell phone works right, you >> might try plugging in your modem there. >> I hope one of these ideas solves your problem. >> -John Sangster, jhs@mitre-bedford.arpa