PPP without a modem


I tried setting up a PPP connection via the PPP port on the R1. The goal here was to see if it was possible to set up a PPP on a serial connection without using 2 modems back to back. The reason is a customer who’s cusomter base already has his equipment using serial via 2 - RS485 converters back to back. I think it is a lousy way to connect, but he’s the customer. Anyway, does a PPP driver such as in windows have to have a modem (with the exception of the modem responses) to actually make a PPP connection to the R1/R2? I am using 9.1b with an R2. If I understand what a PPP connection is, it is simply a means of handshaking and simulating an ethernet connection over essentially a serial network, right?


Hi Barrett,

We have an existing request in our system to “Implement Opto Serial Transport protocol (OST),” which I believe is what you seek. It requests:

“… PPP without requiring the use of AT commands (dial-up modems). The real issue is that sometimes it is necessary to be able to communicate from an S1 controller to another S1 or to Ethernet brains via a serial connection… Customers have typically tried to implement this via PPP only to find out that PPP requires the use of dial-up modems. In the PAC Family, this would apply to the S-series and R-series. The EB-series could not be included because EB brains do not have a serial port.”

Sound like your situation? Odds of this getting bumped up on the priority list will go up, of course, if you (and others) will tell me how many gazillion S1s you’ll buy if only we’d implement this.

But perhaps there’s another way to solve this problem? What are you connecting this R1 to, the PC running PAC Project, I’m guessing?

Good question!


In the case of peer to peer that you mentioned, it can be done via serial to serial now, however to do so means creating a handle and all the issues that go with serial comms. I can see why they would like to make that happen.
In my case I am just tryng to make Pac Display connect to the R2 via serial since that is what may be in place at the sites where this equipment will end up replacing an older unit that used an LC4 (since mid '80s). Their reaction when I tell them that it involves modems is one of “oh, no, not that again”. Since many of their cusomters have 485 in place, I was just trying to find a way to make that happen. On the other hand, I set them up with a MikroTik RB411 wifi radio in the pipeline flasher that talks to a Fujitsu Q550 tablet running Pac Display and works and looks perfect. They may yet give into the wifi system all the way but for now I am trying to solve this if possible. Of course the other method I considered was just use a couple of Ethernet/485 serial bridges and that will also get it done.
I gather that the reason the R series will not work is that their code behind the scenes will not complete the logic to the point where it can connect via PPP to the windows PC? I suppose the same is true for the PC? In other words, the logic on either side will not get to the actual PPP handshake unless their modem commands are responded to? If so, then it’s really not worth the effort, otherwise I am open to suggestons.


Yes, both the “master” and “slave” portion of the OTS would need to be implemented on the R series. But I like your wifi solution! That opens up even more possibilities…