| Posted By
Badco
on 2016-06-08
11:22:11
|  Plus 4 RS232 issue?
I am playing around with the RS232 programming on the plus 4, and I am trying to just do some rudimentary testing... I am plugging an Aprotek Minimodem C 24 to the plus 4, and then doing a simple open the device, read/write in basic...
The Transmit side seems to be working fine, when I hit a key, the TX led flashes, if I send an AT command the TX flashes... then the RX flashes (sending back the ok from the modem)
However, nothing is ever picked up on the get# out of the input buffer.... I am confused as looking at the pinouts te RX bytes should be going into the buffer in order to be pulled out with the get# call... but nothing ever comes out.
This is a used plus 4, so maybe its a hardware problem with the plus 4 itself, but I just want to make sure its not some difference between the plus4 and 64/128 that's the root cause. I know the 1670 has an explicit switch to turn off the carrier detect signal so it will work with the plus 4... but in my case there is no carrier at all... so I would assume the data being RX should be in the input rs232 buffer and the GET# should retrieve it, but it doesn't.
Anyone have any ideas?
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Posted By
SVS
on 2016-06-08
12:33:22
 | Re: Plus 4 RS232 issue?
There are some info to know on RS232 of the Plus4.
1) You have to OPEN it by the format:
OPEN #LogicFile,2,0,R1,R2
#LogicFile = Logical file number (2…14)
R1 = Control Register
R2 = Command Register
2) XON / XOFF settings: write a non-zero value on $FC / $FD
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Posted By
badco
on 2016-06-08
13:25:17
| Re: Plus 4 RS232 issue?
Yes, I did step 1, didn't know aout the XON/XOFF stuff, no sample program I found for the plus 4 mentions this... but given the data is successfully Transmitting, I am dubious that that will solve the problem, but will give it a shot.
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Posted By
JamesC
on 2016-06-08
16:24:24
| Re: Plus 4 RS232 issue?
The userport on the Plus/4 is different than on the 64 or 128, which is why the 1670 has the switch to make it work on any of these.
Aprotek modems were never intended for the Plus/4 so they have no similar switch. Consider your C24 to be 64/128 only.
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Posted By
SVS
on 2016-06-10
14:53:03
| Re: Plus 4 RS232 issue?
There were, at time, some comm programs: Terminal, BBS term+, Plus4-online, etc. I suppose using the RS232.
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Posted By
badco
on 2016-06-10
16:23:58
| Re: Plus 4 RS232 issue?
Yes I know the pinouts are slightly different, but given the 1670 only turns off the Carrier Detect, and I have no carrier signal in this test scenario, I assume this should work... but it isn't.
Good point on other terms, let me try with some of those.. but eveything I read says what I am doing should be working.
I have ordered some RS232 loopback and db 25 breakout boards so I can test it raw, not through a modem, and play with the pinouts etc.
Everything I read says what I am doing should be working, so I am wondering if its just this plus 4 has a problem... but its the only one I have... so can't just try a different one.
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