But for more conventional stage rigging jobs, the standard solution for years has been to use special controllers that coordinate the movements of many hoists from one central location.

Technicians can operate many hoists from one controller box. But controllers can also coordinate groups of hoists lifting single loads and synch lifting operations to stage cues. Controllers can help riggers adapt a show for a different venue, without having to rewrite the entire hoisting programme.

Liftket’s Chainmaster, Verlinde and now Columbus McKinnon offer controllers fit to their stage chain hoists.

Chainmaster’s controller was first developed in 1993, said managing director Frank Hartung, when he and an engineer friend could not find anything on the market that might help meet the BGV-70 German rigging standard, which now has become BGV-C1. The system uses a BUS data network to send information to data modules mounted on the hoists. The company has since sold 150 customised computer systems, with some systems controlling 40 or 50 hoists, and some many more.

Verlinde is currently in the process of finding a supplier to use for a new generation of modular controllers since its previous supplier of the R8CPUs ceased production after seven years.

Hans van der Moolen, Verlinde Stagemaker manager, said that the company has retained enough units to be able to service them, and can also get spare parts if necessary. He expects to have a new product by September.

In the meantime, the company has been working to tailor-make non-modular PLC controls for hoists. “It sounds strange, but modular systems are slightly more expensive than tailor-made ones,” he said.

Columbus McKinnon continues to promote its Pro-Commander controller range, launched late last yaer, to work with its range of fixed-speed Lodestars and variable-speed Vari-Star hoist. “What we realised was that as good as our chain hoist is, with nothing to plug it into that is not cost-effective or desirable, it won’t sell,” Forbes-Black said. CM also decided to get involved because the costs of developing a system compatible with the German rigging standard, BGV C-1 (see p 19) would be too much even for a country-wide distributor to bear.

The most basic CM product is a manually-operated control box. The Pro-F offers control of fixed-speed hoists, and the Pro-V variable-speed hoists. Hoists are fed with one combined 24-pin power/control/data cable with a Harting connector. The control boxes can be daisy-chained to control up to 96 hoists, in a standard configuration. In total, the company has sold 400 channels of controller since launch. The controller is made by German stage engineering company Fuelling and uses Mitsubishi drives.