Hand Held Communicator Registers

D9.0 SAFE, WORKING, OFFLINE, DEFAULT, Registers

Introduction to Registers

From the FUNCTION screen, whilst interrogating an MSM400 control unit, there is a selection titled “BACKUP”. This allows the data now stored in the WORKING register (i.e. the MSM400 control unit data) to be transferred to a separate secure memory, to either retain it while making changes to the MSM400 control unit (i.e. as a “revert to the original program” insurance data store) or to save it in memory so that it can be copied or consulted back in the office. The registers available are

WORKING REGISTER

This is literally the work sheet where all work is done – all changes made to the parameters on the SMART Communicator keyboard are made to the data in the WORKING Register. While the Communicator is attached across the 4-20mA loop, the WORKING register is exactly the same as the MSM400 control unit memory, so all changes made to the WORKING register are also made to the control unit itself. The MSM400 control unit memory and the WORKING register in the SMART Communicator are identical. If communication between the two units fails, then changes attempted in the WORKING register will be rejected.

Note : The SMART Communicator can be unaware of changes to the MSM400 control unit memory made by (a) a Primary Master (such as Mobrey H-View) also attached to this control unit loop, and (b) the local zero and span on the MSM400.

The data existing in the WORKING register is overwritten (and therefore lost) when new data is loaded from another register, or when the SMART communicator is reconnected to an MSM400 loop, because the start up routine will load this new MSM400 memory into the WORKING register. To save any data that has been entered in an “Off-loop” state (i.e. back in the office) the data must be held in the OFFLINE register (see below).

It is recommended that the data in the WORKING register is transferred OFFLINE before disconnection of the SMART communicator from the loop, if it is likely to be needed for reference back in the office. However, the data in the WORKING register is retained in the Psion memory after this disconnection, and can still be interrogated until overwritten by new data.

SAFE REGISTER

The SAFE Register is literally a register where the current MSM400 calibration data can be stored and kept SAFE, while changes are made on the WORKING register and the SMART Communicator is attached to the loop. If these WORKING register changes then prove ineffective or not required, the SAFE register data can be recalled into the WORKING register (and therefore to the MSM400 control unit) to reset all the MSM400 parameters to their original values – i.e. the values in the control unit when the last “Backup” operation transferring the data to the SAFE register was carried out. The data in the SAFE register can only be loaded into the WORKING REGISTER when the communicator is attached to the same MSM400 control unit that was the source of the data – i.e. the control unit with the same unique identifier (D08). It is not possible to transfer programmes between instruments using the SAFE register.

The SAFE register is retained even when the Communicator is disconnected from the loop, powered down, and then reconnected to another loop, collecting new data in the WORKING register. It is not accessible until the correct control unit loop is interrogated, so that the check on the D08 Unique Identifier has been satisfied.

OFF-LINE REGISTER

This is the register used for transfer of programmes between one unit and the next, or from a programme developed on the SMART Communicator at the office desk, stored OFF-LINE and then down loaded into an MSM400 control unit on the plant later. Such data transfer is achieved by connecting the SMART Communicator across the relevant MSM400 loop, loading the WORKING register with the current MSM400 program (see below) then transferring the OFF-LINE stored data into the WORKING register – this overwrites the previous programme in the MSM400 (both the control unit memory and the WORKING Register).

IP258