The EPICS process variable gateway -- Version 2.
The EPICS Process Variable Gateway is both a Channel Access Server and Channel Access Client that provides a means for many clients, typically on different subnets, to access a process variable while making only one connection to the server that owns the process variable. It also provides additional access security beyond that implemented on the server. It thus protects critical servers while providing suitably restricted access to needed process variables. The original version of the Gateway worked with EPICS Base 3.13 but required a special version, since the changes necessary for its operation were never incorporated into EPICS Base. Version 2 works with any standard EPICS Base 3.14.6 or later and has many improvements in both performance and features over the older version. The Gateway is now used at many institutions and has become a stable, high-performance application. It is capable of handling tens of thousands of process variables with hundreds of thousands of events per second. It has run for over three months in a production environment without having to be restarted. It has many internal process variables that can be used to monitor its state using standard EPICS client tools, such as MEDM and StripTool. Other internal process variables can be used to stop the Gateway, make several kinds of reports, or change the access security without stopping the Gateway. It can even be started on remote workstations from MEDM by using a Secure Shell script. This paper will describe the new Gateway and how it is used. The Gateway is both a server (like an EPICS Input/Output Controller (IOC)) and a client (like the EPICS Motif Editor and Display Manager (MEDM), StripTool, and others). Clients connect to the server side, and the client side connects to IOCs and other servers, possibly other Gateways. See Fig. 1. There are perhaps three principal reasons for using the Gateway: (1) it allows many clients to access a process variable while making only one connection to the remote server, thus reducing the load on critical IOCs or other servers; (2) it provides convenient access from one subnet to another; and (3) it provides extensive additional access security. It also has other capabilities, such as providing aliases or renaming for process variables. In addition to providing access to process variables in other servers, the Gateway publishes its own process variables, which allow it to be controlled and monitored using EPICS tools, such as MEDM and StripTool. Owing to these process variables, you can have a very intimate knowledge of what is happening internally in the Gateway.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 982592
- Report Number(s):
- ANL/ASD/CP-116050; TRN: US1005329
- Resource Relation:
- Conference: 10th International Conference on Accelerator and Large Experimental Physics Control Systems; Oct. 10, 2005 - Oct. 14, 2005; Geneva, Switzerland
- Country of Publication:
- United States
- Language:
- ENGLISH
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