Turning on RS423 kills FPS

[nelgin]

I have a physical modem connected to COM3 of my Windows 10 PC. It works fine in a regular terminal emulator.

In BeebEM I load CommStar into SWR then CTRL-F12

Next I go into the setting and select COM3 as the comm port and then check (enable) RS423 ON/OFF.

At that point, the FPS drop from 40's to 0-1 and response is slow for typing, playing sounds, loading disk, etc. CommStar is unusable.

I'm not sure what information you may need to debug this, so let me know and I'd be happy to provide it.

[chrisn]

Thanks, I'll try to reproduce it here. I don't think anything changed in recent releases to cause this problem. Help fixing this is welcome, if you're interested to look into the code.

[nelgin]

I wouldn't even know where to start looking but I'm more than happy to throw in any debug statements or do testing etc. I haven't tried this in previous versions so not sure if it's a regression or not. I guess I can grab an older version.

[nelgin]

Just loaded 4.14 and it's the same, so the issues goes back a fair way. Maybe it's something to do with modern serial hardware? no idea.

[nelgin]

A bit more background. I have a regular serial port on COM1. I use it with putty to connect to my linux as a serial console. If I use this com1 port. then BeebEm works fine when turning on rs423.

My modem is a USB device. It was originally configured for COM7 but BeebEM won't let me select. that. I moved it to COM4 and that gave me the 0 FPS. I then decided to try and move it to COM2, which I did, and rebooted. Same issue. So this may have something to do with it being a USB modem rather than using a COM port directly.

Not sure what else I can give you to help.

[insleys]

The only thing I can think of in relation to the fast that it’s a USB device is that the driver architecture for USB serial isn’t great in Windows. The behaviour in BeebEm sounds like something is blocking in the code waiting for a response which is usually instantaneous, but isn’t in the case of your hardware. While this is possibly a problem with BeebEm code, it’s worth exploring whether you can “solve” the problem by making your device behave better. The reason I say that is because I had a similar problem with a USB serial device talking to a UPS a while back. The monitoring software had noticeable UI lag and high CPU utilisation. It turned out that the USB serial device had defaulted to 150 baud and the software wouldn’t override that. In the device settings under Device Manager, I experimented with higher baud rates and, boom… the issue went away. Not saying that’s a “fix”. Not saying it’ll work. But worth a try, if only to support my theory that BeebEm is expecting certain timings and not getting it because of the hardware driver. From: nelgin ***@***.***> Sent: 25 January 2022 06:04 To: stardot/beebem-windows ***@***.***> Cc: Subscribed ***@***.***> Subject: Re: [stardot/beebem-windows] Turning on RS423 kills FPS (Issue #99) A bit more background. I have a regular serial port on COM1. I use it with putty to connect to my linux as a serial console. If I use this com1 port. then BeebEm works fine when turning on rs423. My modem is a USB device. It was originally configured for COM7 but BeebEM won't let me select. that. I moved it to COM4 and that gave me the 0 FPS. I then decided to try and move it to COM2, which I did, and rebooted. Same issue. So this may have something to do with it being a USB modem rather than using a COM port directly. Not sure what else I can give you to help. — Reply to this email directly, view it on GitHub<#99 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AI2TTM5EEEITF63WBCCDBGDUXY4N7ANCNFSM5MRRUVEA>. Triage notifications on the go with GitHub Mobile for iOS<https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android<https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.******@***.***>>

[nelgin]

I'm pretty sure that's not the problem. When I eventually connect to the modem it definitely isn't 150 baud. The fastest commstar will talk to the DTE is 9600 anyway so I can't go any faster than that.

[nelgin]

I have found an acceptable work around. Poking around http://com0com.sourceforge.net I found the hub2com project. This will listen on a given tcp/ip port and redirect to a com port.

Running com2tcp-rfc2217.bat COM2 25232 from the command prompt started the listener then I just selected the IP:25232 option in BeebEM and connected.

I thought I'd include a blast from the past :)