R
Regular readers of this list will be well aware of my long running quest to find an industrial communications protocol that is suitable for using
'across the board' i.e. from IP level down to serial connections to field devices.
Commonly used solutions generally do not achieve this. OPC, for example, is an internal windows protocol, it does not take you into field devices
and would perhaps be better described as a 'device driver'. Modbus, Profibus, CAN et al take you from the field level to the controller, but not onto the information highway. Of course Profibus also have their 'industrial ethernet', but the only working example of this glorious
product seems to require so many high priced elements that it just prices itself way out of my market, as does OPC in a way, which appears to me to make life easier for SCADA software producers and force costs onto end users.
Really it should not be too hard to do this, actually I already do using my own protocols. But while discussing this in the past somebody
pointed out to me that MODBUS now has a TCP/IP transport, and like the original protocol this is openly published and royalty free.
Well, I checked this out and found that there is not only a TCP/IP transport for MODBUS queries, but also a messaging protocol. What's more
they have kept things simple so you do not get unreliable bloatware and it should be easy to implement custom gateways such as querying an OMRON PLC from a an OPC SCADA package.
So now I feel like I have received one of those 'earn $2000 a day in your spare time' emails, it sounds too good to be true. Why is everybody not using it? Now while I know a lot of people are using MODBUS on a wide range of products, by and large it has been in use as a async serial based field to controller product. So, does anybody have any success/disaster stories regarding the use of MODBUS frames or messaging over TCP/IP networks?
I have been programming TCP/IP for years, and it LOOKS valid to me, but appearences are often deceptive!
'across the board' i.e. from IP level down to serial connections to field devices.
Commonly used solutions generally do not achieve this. OPC, for example, is an internal windows protocol, it does not take you into field devices
and would perhaps be better described as a 'device driver'. Modbus, Profibus, CAN et al take you from the field level to the controller, but not onto the information highway. Of course Profibus also have their 'industrial ethernet', but the only working example of this glorious
product seems to require so many high priced elements that it just prices itself way out of my market, as does OPC in a way, which appears to me to make life easier for SCADA software producers and force costs onto end users.
Really it should not be too hard to do this, actually I already do using my own protocols. But while discussing this in the past somebody
pointed out to me that MODBUS now has a TCP/IP transport, and like the original protocol this is openly published and royalty free.
Well, I checked this out and found that there is not only a TCP/IP transport for MODBUS queries, but also a messaging protocol. What's more
they have kept things simple so you do not get unreliable bloatware and it should be easy to implement custom gateways such as querying an OMRON PLC from a an OPC SCADA package.
So now I feel like I have received one of those 'earn $2000 a day in your spare time' emails, it sounds too good to be true. Why is everybody not using it? Now while I know a lot of people are using MODBUS on a wide range of products, by and large it has been in use as a async serial based field to controller product. So, does anybody have any success/disaster stories regarding the use of MODBUS frames or messaging over TCP/IP networks?
I have been programming TCP/IP for years, and it LOOKS valid to me, but appearences are often deceptive!