Sams4s protocol project

We first got a Sam4s till a few years ago when we needed one for our market events. We ended up with an ER-230 a nice compact ECR with built in battery, ideal for market and outdoor events and its small footprint was even better. The till had an RS232 port and could be connected to a PC, but it was not really obvious where to get the software from and no protocol documentation was available. After some goggling around I found software for the ER-230 and it seemed to work fine. I could tweak the things that needed tweaking and I left it at that. This year we opened our first shop and needed a ECR for the shop. So again we went for a Sams4s, this time the ER-380M which seemed to offer everything we needed or though we would need in a shop ECR and the prospect of RS232 comms was also good as we had ideas over automatic stock control and barcode scanning of products.

In order to get some kind of integrated stock control we would need to talk to the ECR via RS232 and this is where the trouble began. Going to the same site as i got the software for the ER-230 from I downloaded a version for the ER-380M and very soon found it was slightly incompatible and could corrupt the PLU file in the till. There was another version of the software from the same site but it also had the same issue. After extensive googling I determined that my version of the ERC software v2.5 was not compatible with either of the versions of PC software I could download, and also apart from a few on ebay that did not list version numbers or compatibility it was really non-obvious where to even purchase the software from.

So with this level of success and no prospect of even just purchasing what we required, I decided to start doing it myself. So using a RS232 protocol sniffer I started to decode what was being sent each way between the ECR and the PC and this leads to the following project :-

An opensource implementation of software to program Sams4S tills

Currently we are working with:-

an ER-230

an ER-380M v2.5

Documentation will be appearing below and code can be found on github at


This protocol is NOT OFFICIAL documentation and may contain errors and omissions or simply may not do as intended.  It may corrupt your ECRs programming or cause loss of information. This is purely an experimental project for my own uses that I have made public in the hope that it is useful to others. If you decide to use this information you must accept all responsibility of any problems that may occur in using this code and documentation.

This documentation has been generated by pure reverse engineering by watching the protocol on the wire, I have no access to any official documentation from SAMS4s and I have no idea where you would even get such things.

Command format

PLU File format

Clerk File Format

Leave a Reply