Setup guide

Setting Configuration Parameters

Redundancy Transfer

Unit A Addr

This must be an IP address corresponding to an Ethernet port on the

‘A’ I/O Expansion Rack in a redundant pair.

Unit B Addr

This must be an IP address corresponding to an Ethernet port on the

‘B’ I/O Expansion Rack in a redundant pair.

MODBUS Write Access

Serial Failover

Enabled

Normally, should communications be lost between the host

ControlWave and the I/O Expansion Rack, the I/O points are set to the

‘safe’ state described under “Host Comm Loss Timeout”. When

“Serial Failover Enabled” is checked, however, write control through

serial MODBUS communications are allowed with the I/O Expansion

Rack, even though communications with the host ControlWave have

been lost. This allows control operations to continue via the I/O rack,

until Ethernet communication with the host can be re-established.

This is also true in cases where a redundant pair of I/O Expansion

Racks have been configured; a failover from the on-line rack to the

standby rack will not occur just based on a loss of communications

with the host, if serial MODBUS communications are still active.

In order for the “Serial Failover Enabled” feature to work, MODBUS

communications must have been fully pre-configured, and ready to use

when communications are lost with the host. If serial MODBUS

communications fail, and the user configured “Host Comm Loss

Timeout” has expired, all outputs will be set according to the “Host

Comm Loss Timeout” description, above.

NOTE: Serial MODBUS read requests are unaffected by the “Serial

Failover Enabled” check box. Reads are always allowed. Serial

MODBUS writes are only allowed when “Serial Failover Enabled” is

checked.

The “Serial Failover Enabled” feature requires firmware 04.00 or

newer.