Hey pradeeban,

Fixes #244.

The write() function behaved differently for ZMQ and file-based communication.

In the file-based path, [simtime + delta] is prepended before writing the data.
But in the ZMQ path, the value was sent directly without the simtime prefix.

Since read() always expects the first element (inval[0]) to be simtime, this caused problems in mixed setups where one component uses ZMQ and another uses file-based communication. In those cases the first data value could be interpreted as simtime, resulting in incorrect data and one fewer value being returned.

To fix this, the ZMQ write path now prepends simtime + delta to list payloads so that it behaves the same as the file-based implementation.

Updated logic:

if isinstance(zmq_val, list):
payload = [simtime + delta] + zmq_val
zmq_p.send_json_with_retry(payload)
simtime += delta
else:
zmq_p.send_json_with_retry(zmq_val)

Changes in this PR:

• concore.py – prepend simtime to ZMQ list payloads in write()
• test_concore.py – updated test to expect the simtime prefix

Testing:

• All 25 unit tests pass locally
• Non-list ZMQ payloads remain unchanged for backward compatibility
• Existing retry logic and error handling are preserved