Hi everybody,
and thanks to all: in this forum I've often found help, reading the posts. Now I need help again to make the most of MSG instructions in SLC500 for a project that is unusual for me.
This is the "architecture": two pumping stations, 1.5 km apart, each one controlled by an SLC5/04 and supervised on site with RSView through DH+ channel.
Each plant must be controlled also from the remote one.
The odd thing is: the customer won't buy anything but a two-wire copper cable to connect the two CPUs. Obviously this was decided after the CPU were bought, programmed and tested for a DH+ communication between them and with RSView
.
So...
The two modems I'm using work pretty fine (Westermo, 19200 bps), the MSG instruction doesn't. Sure not 4 at a time. Communication locks. Ok, it's serial communication, let's say I can use two MSG for each slc ... but no, it doesn't work, the error bit is too often on (ok, ok, it's point-to-point, I can't have both-ways communication) . Maybe 4 MSG in one SLC, the master? It's the same, error on, too often.
By the way, the "Comms servicing bit" and "Message Servicing selection" bits are cleared.
I've plenty of data to exchange (200 integers, 30 floats) and I'm using the ladder I found in this forum to execute 1 MSG at a time (4 read MSG in sequence, write commands on exception). It works. 15- 20 seconds to send a command with feedback, controlling the 2 plants from 1 master, not the reverse... and my testing system is only .5 m apart instead of 1.5 km!!!
Please, do you know how can I improve the use of msg?
In particular, do you have suggestions on how to give higher priority to critical data such as alarms and interlocks?
Thanks for your patience if you've read all this...
Ciao.
and thanks to all: in this forum I've often found help, reading the posts. Now I need help again to make the most of MSG instructions in SLC500 for a project that is unusual for me.
This is the "architecture": two pumping stations, 1.5 km apart, each one controlled by an SLC5/04 and supervised on site with RSView through DH+ channel.
Each plant must be controlled also from the remote one.
The odd thing is: the customer won't buy anything but a two-wire copper cable to connect the two CPUs. Obviously this was decided after the CPU were bought, programmed and tested for a DH+ communication between them and with RSView
.So...
The two modems I'm using work pretty fine (Westermo, 19200 bps), the MSG instruction doesn't. Sure not 4 at a time. Communication locks. Ok, it's serial communication, let's say I can use two MSG for each slc ... but no, it doesn't work, the error bit is too often on (ok, ok, it's point-to-point, I can't have both-ways communication) . Maybe 4 MSG in one SLC, the master? It's the same, error on, too often.
By the way, the "Comms servicing bit" and "Message Servicing selection" bits are cleared.
I've plenty of data to exchange (200 integers, 30 floats) and I'm using the ladder I found in this forum to execute 1 MSG at a time (4 read MSG in sequence, write commands on exception). It works. 15- 20 seconds to send a command with feedback, controlling the 2 plants from 1 master, not the reverse... and my testing system is only .5 m apart instead of 1.5 km!!!
Please, do you know how can I improve the use of msg?
In particular, do you have suggestions on how to give higher priority to critical data such as alarms and interlocks?
Thanks for your patience if you've read all this...
Ciao.
