Many people on UNIX systems have no PC to perform a firmware update, or, put otherwise, most CD-writer manufacturing companies don't provide UNIX software to perform the firmware update . . . That's why Jörg Schilling (the guy from cdrecord) ported Plextor's PXUpdate utility to UNIX.
To perform the upgrade, you need the following :

• at least 1 Plextor CD-Writer
• generic SCSI cdrom support (but you already needed that for cdrecord)
• the PXUpdate tool
• the firmware specific for your model of Plextor drive

The first item you will have to buy yourself, but PXupdate can be found here and firmware for different Plextor drives here. PXUpdate is available for Linux, FreeBSD, AIX, MacOS X, SunOS, IRIX and a few other UNIX types.

You have to make sure that no other system activity will interrupt the firmware update procedure. You have two diffent options to do this.
If you want to be 100% sure, do it in single user mode. This can be done with telinit 1 on a Linux system.
In case you cannot put the machine into single user mode, at least unmount any media that is inserted into the drive that needs to be updated.
Also, don't forget to unzip the firmware file you just downloaded.

You must be root to do this ! When invoked with the -l switch on my system, PXUpdate showed the following :

[root@stargate /tmp]# ./pxupdate -l __________________________________________________________________________ | PXUpdate V1.27 Jörg Schilling 02/02/09 | | Based on V1.12 (c) PLEXTOR SA/NV (EUROPE) 99/11/9 | | Port to UNIX (c) Jörg Schilling 99/11/15 | | Plextor Firmware Update program | __________________________________________________________________________ Linux sg driver version: 3.1.24 PLEXTOR CD-R PX-W1610A V1.02 (HA:0 ID:0)

That looks good. Now, to perform the upgrade, type PXUpdate at the command prompt, followed by the filename of the firmware file.

[root@stargate /tmp]$ ./pxupdate W1610105A.bin

After scanning the file to see for which drive it is intended, the program asks if you want to upgrade them. You can select y (yes), n (no) or a (all).

Upgrade Plextor drive at HA:0 ID:0? (y/n/a) y WARNING! Firmware updates should be done in single user mode. If you cannot put your machine into single user mode, unmount and remove any media from the drive and stop volume management. Continue? (y/n) y Current firmware version: 1.02 Upgrade PX-W1610A (HA:0 ID:0) in progress...Done

The drive's LED will light up during the upgrade. When done, type Ctrl-C to return to the command prompt. You can then check again with ./pxupdate -l if the drive reports the new firmware version. To be sure the drive still works fine, just burn a CD.
NOTE: if you upgrade an ATAPI drive and DMA is active , you will have to cold start the PC after the upgrade in order to make the drive work again. That's all folks !