Here is what you need to do in order to send "message" command to an hai controller.

1) You need to set the HAI serial port setting that is tied to your msc-400 controller in "pro-link" mode in your hai configuration.

"Omni link" mode is quite complicated and requires authentifications, login and most of all crc check calculations so it is really difficult to build a string.

On the other hand, "pro-link" is super easy to make work so apply this change to your hai rs232 port.

2) In your hai program, you'll need to create "messages". For example, create two messages called "away" and "off".

3) You'll need to create programming blocks in the hai controller that would look like this:
WHEN RECEIVE MESSAGE arm
THEN SECURITY MODE IS AWAY

WHEN RECEIVE MESSAGE off
THEN SECURITY MODE IS OFF

Download your programming blocks to your hai controler.

4) In your urc controller (which I am not familiar with), just create a text string with the word "away" and "off" that you are going to send on the rs232 port. Once you send these simple "words" text string to the rs232 port on the hai controller, it will execute the logic and arm or disarm the system.

You could do the opposite way also to get two way confirmation messages. In that case, you would need to do the following:

1) Create two new messages "armed" and "disarmed"

2) Create two programming blocks like this:
WHEN OFF (security, any codes, off)
SEND MESSAGE disarmed (send, message, select which rs232 port)

WHEN AWAY (security away)
SEND MESSAGE armed (send, message, select which rs232 port)

3) When the action of arming or disarming the hai, it will send the text "disarmed" or "armed" to your msc400. Once you receive theses messages on your msc-400, you can probably apply or remove visual confirmations on a two way touch panel.

For ANY action you need to make a "message" in your hai controller. You can then control ANYTHING you want on the hai omni pro II controller. The only limit is the quantity of messages. You can control "buttons", "lights", "security", "relays" or trigger any other events on your hai controller...

One last thing. Do NOT forget that connecting two processors together requires a crossover serial cable. The TX of one needs to go in the RX of the other one and vice-versa. Otherwhise, this will never work.

Hope this helps !!!